In sand casting, sand is the basic modeling material, and its amount is huge, often a multiple of the quality of the casting. There are also different types of foundry sand, and the differences are significant. Among them, the largest amount is quartz sand, also known as silica sand. The main mineral of quartz sand is quartz-namely silicon dioxide (SiO2). In high-quality quartz sand, the total SiO2 content can be as high as 99.5%, and the rest are impurities such as feldspar and biotite.
It is understood that quartz sand for foundry is the largest amount of raw foundry sand. It is an important modeling mineral material and is widely used in the casting of steel and non-ferrous metals. The total output of castings in China has ranked first in the world for many years. According to statistics, for every 1 ton of qualified castings, 1-1.3 ton of quartz sand is needed, and the country consumes more than 20 million ton of new sand every year.
Regarding the regulations of foundry standard sand, the content of SiO2 in foundry sand should be greater than 90%. Generally speaking, the properties of quartz sand formed under different geographical environments are also different. Because quartz has high fire resistance and hardness, and its excellent process performance can meet various basic requirements of casting production, it can not only be used for traditional clay sand modeling, but also can be used for advanced modeling and molding such as resin sand and coated sand. Because of the core-making process, quartz sand is widely used in foundry production. Many large modern foundries are adopting a large number of molding processes such as resin self-hardening sand, which has made the use of siliceous quartz sand continue to increase in recent years.
As an aggregate of modeling materials, the performance of quartz sand must directly affect the quality of castings. Foundries generally have many basic requirements for the selection of casting sand. It can be seen that quartz sand plays a pivotal role in casting production. Because of this, the research and discussion on the various physical and chemical properties of quartz sand and the casting process performance has always been one of the scientific research topics that the casting industry scientists pay close attention to.
The quality requirements of the foundry industry on quartz sand
According to rough statistics, foundry sand used in the machinery manufacturing industry accounts for about 30% of the world's total output. The general requirements for the composition of quartz sand abroad: cast steel sand: SiO2≥98%, K2O+Na2O≤0.5%, CaO+MgO≤1.0%, mud content ≤0.2%, the most used particle size is: 0.1～0.6 mm , Some larger than 0.6 mm and smaller than 3.35 mm are also used. Generally, natural sand with better spheronization degree is used, and machine-made sand is used less.
At present, one of the processes for producing various metal products is the resin sand casting process, which is to pour molten metal into a hollow sand mold. Among them, silica sand is the main modeling material used to produce disposable sand molds in the resin sand casting process. By adding a binder and other substances, the sand particles are glued together to form a sand mold with mechanical strength.
With the development of the foundry industry at home and abroad, especially the automobile industry, various resin binder systems have come out one after another. These resin binder systems use a mixture of sand, binder, and curing agent to prepare sand molds. During the mixing process, the binder and curing agent immediately start to react, and slowly mold the sand into a sand mold or core with a certain mechanical strength. Once it has sufficient strength, it can be used for casting. The resin binder system can be cured and hardened in a short time. In addition, it eliminates the difference between sand mold manufacturing and core material manufacturing. Therefore, the resin bonding system is suitable for the automated production of small and medium batches of complex castings.
Silica sand powder processing technological process
Phase one: raw material crushing Silica sand blocks will be crushed to 15mm-50mm fineness by crusher.
Phase two: grinding Silica sand material will be sent to the storage hopper by the elevator, and than the feeder will send the material to the main mill for grinding.
Phase three: classifying Ground material will be classified, coarse powder will fall back to the main mill to be ground again.
Phase four: production collecting Qualified powder will flow with the air and be collected in the dust catcher, then the finished powder will be transported to the product storage bin through discharge port. Lastly, the powder will be loaded by tank car or packed by packing machine.
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