The main raw materials for silica fine powder include silica sand, slag material, wood shavings, food bowls and furnace materials, etc. During the firing process, the particle size, purity and proportion of raw materials will affect the performance and weight of silica fine powder. The bottom surface is prepared with raw materials such as powdered silicon powder.
1. Silica sand, also known as quartz sand, is a commonly used raw material for smelting SiC. River sand and sea sand are used to smelt black SiC, while vein quartz is used to smelt green SiC. The particle size of silica sand has an important impact on the output and power consumption of SiC, so silica sand with appropriate quality and fine particle size should be selected.
2. Carbon mainly provides the carbon element required to generate silicon carbide micropowder. Petroleum coke, asphalt coke and low-ash anthracite are commonly used as raw materials.
3. Wood powder (hardwood chips) is used to increase the ventilation in the furnace and expand the reaction area.
4. The content of salt is 97% to 99%, and the particle size is less than 2mm. When adding it to smelting green SiC, it can accelerate the removal of impurities and act as a purifier and catalyst. It is not used when smelting black SiC.
Equipment and production methods:
The resistance furnace is the main equipment for smelting silicon carbide powder. The smelting process methods include the new material method and the smelting material method. The new material method is to directly load the prepared raw materials into the reaction zone of the resistance furnace to smelt silicon carbide powder. The smelting material method is to load the prepared raw materials into the reaction zone of the next furnace for smelting.
The process flow of silicon carbide powder production is divided into: batching → charging → smelting → cooling and stoking → mixing and desalting → unloading and grading → granulation.
Silicon carbide granulation production process
Generally, abrasives with a particle size of F4 to F220 are called abrasives, and abrasives with a particle size of F230 to F1200 are called micro powders. Abrasives are processed by screening and grading, and micro powders are processed by hydraulic grading.
The granulation process includes: crystal block crushing → screening → water washing → acid washing → alkali washing → magnetic separation → shaping → calcination (drying) → fine screening → inspection and packaging.
The main process of micro powder includes: crystal block crushing → ball milling → screening → water washing → dehydration → drying → hydraulic grading → magnetic separation → fine screening → inspection → packaging.