CN114988412A

CN114988412A - Preparation method of silicon carbide micro powder

Info

Publication number: CN114988412A
Application number: CN202210506697.4A
Authority: CN
Inventors: 于葛亮; 王雷; 谢一麟
Original assignee: Nantong Planck Graphene Technology Co ltd
Current assignee: Nantong Planck Graphene Technology Co ltd
Priority date: 2022-05-11
Filing date: 2022-05-11
Publication date: 2022-09-02

Abstract

The invention relates to the technical field of silicon carbide preparation, in particular to a preparation method of silicon carbide micro powder, aiming at solving the problems of resource waste and pollution caused by solid wastes such as silicon ash and cutting waste, comprising the following steps of mixing the silicon ash, the cutting waste and stone tar, adding a binding agent, fully mixing for 4 hours in a mixer, then preparing the mixture into pellets, and drying the pressed pellets in an oven, wherein the stone tar is excessive, and the adding mass of the cutting waste is 5-50% of the adding mass of the silicon ash; placing the dried pellets into a medium-frequency induction furnace for smelting at the temperature of 1550-; mixing silicon carbide powder with water according to the weight ratio of 1:5-8 to obtain silicon carbide mixed slurry, and uniformly stirring; fully grinding the silicon carbide mixed slurry to obtain silicon carbide micro powder with the granularity D50 value of 0.3-0.6 mu m; removing floating carbon on the surface layer by using the collected liquid, and performing acid-base washing purification; and washing with water and drying to obtain the silicon carbide micro powder.

Description

Preparation method of silicon carbide micro powder

Technical Field

The invention relates to the technical field of silicon carbide preparation, and particularly relates to a preparation method of silicon carbide micro powder.

Background

The silica fume is a solid waste formed by SiO and Si steam generated in the smelting process of industrial silicon and ferrosilicon, which is collected in a dust collecting channel and then contacts with air to be rapidly oxidized, condensed and precipitated. The silica fume (namely the silicon dioxide micro powder) generated in China every year can reach millions of tons. Silica fume is an important inorganic non-metallic material and is widely applied to the fields of concrete, refractory castable, rubber, chemical industry, aerospace and the like. The crystalline silicon diamond wire cutting waste is solid waste generated in the crystalline silicon slicing process, generally more than 40% of crystalline silicon enters the cutting waste in the form of powder. China can generate a large amount of cutting waste every year, and recycling of the cutting waste is also a hot spot at present. Silicon carbide is a refractory raw material with good performance, and is widely applied to the fields of high-grade refractory materials, functional ceramics and the like. Both the silica fume and the cutting waste are solid wastes with extremely small particle size, and the storage or the random disposal of the wastes can affect the environment and the health of people. Therefore, more recycling ways are sought, which is helpful for solving the pollution problem of solid wastes and can also reduce the waste of resources.

There is a need for a method of adding cutting waste to silica fume for the production of silicon carbide.

Disclosure of Invention

Therefore, the invention aims to provide a preparation method of silicon carbide micropowder, which solves the problems of resource waste and pollution caused by solid wastes such as silica fume and cutting waste.

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

a preparation method of silicon carbide micro powder comprises the following steps:

s1, blending the silica fume, the cutting waste and the stone tar, adding a bonding agent with the mass fraction of 3-5%, fully mixing for 4 hours in a mixer, then making the mixture into pellets under the pressure of 12-15MPa, and drying the pressed pellets in an oven at 100 ℃ for 6 hours, wherein the stone tar is excessive, and the adding mass of the cutting waste is 5-50% of the adding mass of the silica fume;

s2, placing the dried pellets in an intermediate frequency induction furnace to smelt for 45min at the temperature of 1550-;

s3, mixing the silicon carbide powder with water according to the weight ratio of 1:5-8 to obtain silicon carbide mixed slurry, and uniformly stirring;

s4, fully grinding the silicon carbide mixed slurry to obtain silicon carbide micro powder with the particle size D50 value of 0.3-0.6 mu m;

s5, removing floating carbon on the surface layer through collecting liquid, and carrying out acid-base washing purification;

and S6, washing with water and drying to obtain the silicon carbide micro powder.

Optionally, in the step S1, the added mass of the cutting waste is 25% of the added mass of the silica fume.

Optionally, in the step S2, smelting is performed at a temperature of 1750 ℃.

Optionally, in step S3, during the stirring, the motor drives the stirring shaft to rotate, the stirring paddle continuously stirs the slurry, and the high-pressure air pipe continuously inflates and pressurizes the slurry, so that the slurry entering the feed port is high-pressure silicon carbide powder slurry.

Optionally, in step S4, the grinding is performed by using a vertical multi-disk grinder, and the grinding medium is monocrystalline silicon carbide particles with a particle size of 2-5 mm.

Optionally, in step S5, the liquid collecting agent is one of a glass water repellent and an organosilicon water repellent.

Optionally, in the step S6, the drying temperature is 100-140 ℃, and the time is 30-50 hours.

The invention has the beneficial effects that:

the addition of the cutting waste materials is beneficial to improving the purity of SiC prepared from the silica fume, and has a promoting effect on reaction, the process is convenient to operate, the working efficiency in production is high, the water consumption is low, the production cost is low, continuous feeding and discharging can be carried out for production, the production capacity is high, the production efficiency is high, the produced product is stable, the quality of the produced silicon carbide micro powder is high, the sintering temperature is low, the sintering density is high, and the requirements in production can be completely met.

Detailed Description

In order to make the technical solutions of the present application better understood by those skilled in the art, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the embodiments of the present application, and it is obvious that the described embodiments are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It is noted that the terms first, second and the like in the description and in the claims of the present application are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It should be understood that the data so used may be interchanged under appropriate circumstances such that embodiments of the application described herein may be used. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

Moreover, some of the above terms may be used to indicate other meanings besides the orientation or positional relationship, for example, the term "on" may also be used to indicate some kind of attachment or connection relationship in some cases. The specific meaning of these terms in this application will be understood by those of ordinary skill in the art as appropriate.

In addition, the term "plurality" shall mean two as well as more than two.

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail with reference to examples.

s1, blending silica fume, cutting waste and stone tar, adding a bonding agent with the mass fraction of 3-5%, fully mixing for 4 hours in a mixer, then making the mixture into pellets under the pressure of 12-15MPa, and drying the pressed pellets in an oven at 100 ℃ for 6 hours, wherein the stone tar is excessive to ensure that a carbon source is sufficient, and the adding mass of the cutting waste is 5-50% of the adding mass of the silica fume;

specifically, the binding agent is hydroxypropyl methylcellulose, and the stone tar is a carbonaceous reducing agent;

analyzing the phase composition of the product by an X-ray diffractometer, wherein the SiC content in the product is obtained by a chemical quantitative analysis method, when the addition mass of the cutting waste is 35% or less of the addition mass of the silica fume, almost only the diffraction peak of SiC exists in the product, when the addition mass is 50% of the addition mass of the silica fume, the diffraction peak of Si appears, and the excessive Si does not react, so that the SiC content in the product is increased and then reduced along with the increase of the addition mass of the cutting waste, and is highest when the addition mass is 25% of the addition mass of the silica fume;

the SiC content in the smelting product gradually increases along with the rise of the temperature and gradually becomes stable after 1750 ℃, which shows that more unreacted raw materials exist at lower temperature, so that the SiC content in the product is lower, the reaction is almost completely carried out at 1750 ℃, and the 1750 ℃ is the optimal reaction temperature; at the optimum reaction temperature, when the addition mass of the cutting waste is less than 35% of the addition mass of the silica fume, the SiC content in the obtained product is obviously higher than that when the cutting waste is not added, which shows that the addition of a certain amount of cutting waste can promote the silica fume to be more completely converted into silicon carbide, and the preparation of purer SiC is facilitated, and the main reasons are that: (1) the temperature for generating SiC by the reaction of Si and C is low, and SiC is easy to generate; (2) the reaction of Si and C is exothermic, can provide part of heat for smelting process, and is helpful for SiO ₂ SiC is generated through reaction as much as possible; (3) the added Si powder can inhibit the occurrence of side reaction to a certain extent, and the yield reduction caused by SiC decomposition is reduced;

specifically, during stirring, the stirring shaft is driven by the motor to rotate, the stirring paddle continuously stirs the slurry, and the high-pressure air pipe continuously inflates and pressurizes the slurry, so that the slurry entering the feeding hole is high-pressure silicon carbide powder slurry;

in the embodiment, a vertical multi-disk grinding machine is adopted for grinding, and grinding media are monocrystalline silicon carbide particles with the particle size of 2-5 mm;

s5, removing floating carbon on the surface layer through a collected liquid, and carrying out acid-base washing purification;

specifically, the liquid collecting and collecting agent is one of a glass water repellent or an organic silicon water repellent;

s6, drying after washing with water at the temperature of 100 ℃ and 140 ℃ for 30-50 hours to obtain the silicon carbide micro powder.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.

Claims

1. The preparation method of the silicon carbide micro powder is characterized by comprising the following steps:

s1, blending silica fume, cutting waste and stone tar, adding 3-5% by mass of a binding agent, fully mixing for 4 hours in a mixer, then making the mixture into pellets under the pressure of 12-15MPa, and drying the pressed pellets in an oven at 100 ℃ for 6 hours, wherein the stone tar is excessive, and the adding mass of the cutting waste is 5-50% of that of the silica fume;

2. A method for producing a fine silicon carbide powder according to claim 1, wherein in step S1, the added mass of the cutting waste is 25% of the added mass of the silica fume.

3. A method for preparing silicon carbide micropowder according to claim 2, wherein in step S2, the silicon carbide micropowder is smelted at a temperature of 1750 ℃.

4. A process for preparing silicon carbide micropowder according to claim 1, wherein in step S3, the stirring shaft is driven by a motor to rotate during stirring, the slurry is continuously stirred by a stirring paddle, and the slurry is continuously aerated and pressurized by a high-pressure gas pipe, so that the slurry entering the feed port is high-pressure silicon carbide powder slurry.

5. A process for producing a fine silicon carbide powder as claimed in claim 1, wherein in step S4, a vertical multi-disk mill is used for the milling, and the milling medium is silicon single crystal carbide particles having a particle size of 2 to 5 mm.

6. The method for preparing silicon carbide micropowder according to claim 1, wherein in the step S5, the liquid collecting agent is one of a glass water repellent or an organosilicon water repellent.

7. The method as claimed in claim 1, wherein the drying temperature is 100-140 ℃ and the time is 30-50 hours in step S6.