[China Glass Net] Silica Sand: In the actual operation of the production of A plant, SiO2>99%, Fe2O3-0:04% and more than 30 mesh particles ≤1% are important control indicators, strictly enforced, and should not be relaxed. Reason: Si02 is almost full in silica sand, and is also the main component in glass, accounting for about 72.5%. Its slightest changes will have a huge impact on glass production. The change of Fe2O3 content will directly affect the fluctuation of Fe2O3 content in the glass composition, which will cause the fluctuation of the transmittance of the glass, produce chromatic aberration, and cause the difference of reflectance and color when the glass is deep-processed. In order to make up for the coating process, it is necessary to adjust the film thickness and re-modulate the color plate, which is obviously not suitable. In addition, fluctuations in the Fe203 content of the glass component cause different effects of the glass liquid receiving radiation and convection heat transfer, so that the melting operation system must be properly adjusted to increase the operational burden on production. Controls greater than 30 mesh particle size ≤ 1% are due to the increase in large siliceous particles, which may result in the production of large amounts of stones in the finished glass.
Dolomite/limestone: Fez03≤0.18% in Dolomite, CaO content is 30.0-31.0%, Mg0 content is 21.0-22.0%, these three are the main control indicators; Fe2O3≤0.15% in limestone, CaO≥ 52.0%, these two are the main control indicators. The particle size index is not very tightly controlled for dolomite and limestone. original
The reason for the strict control of the Fe2O3 content index has been explained in the former silica sand. The control of CaO content in dolomite is based on the actual conditions of raw material process in plant A. There is no reservoir of limestone in the raw material process of plant A. It is transported directly from the mine to the plant by tanker, and then pneumatic conveying directly into the warehouse. Therefore, the test of limestone sometimes cannot Pre-predicted very early before use. If there is fluctuation, it is too late to adjust it so that it can be blended with dolomite to stabilize the CaO in the batch. In the glass composition
Fluctuation in CaO content will cause changes in glass frit, affecting the forming annealing operation and directly affecting production stability. Since dolomite is an anomaly, it introduces a considerable amount of CaO in the glass. For this reason, we can strictly control the CaO content in dolomite. To reduce the impact of fluctuations in CaO in limestone on CaO in glass, stabilize production. The production practice from the A factory proves that this method has indeed achieved good results. Of course, Mg0 and CaO are representative components of dolomite and limestone, respectively.
It is also a matter of course to pay attention as the main control indicator.
Feldspar: In the actual operation of the plant, the Fe2O3 ≤0.3%, AL2O3: ≥15.0%, R20 ≥ "11.0% of which K2O>8.0%, granularity" 30 mesh is 0 as the key control of feldspar in the actual production operation. Reason: Fe2O3, AL2O3 will not be discussed here, focus on the R2O index K2O> 8.0%. The feldspar currently used in plant A is potassium feldspar, the K2O content is much larger than the Na2O content, the test results statistics: K20 is generally Between 8.0 and 9.8, Na20 is between 2.0 and 4.2. According to previous experience, feldspar with relatively close content of K20 and Na20 is usually accompanied by nepheline, or it is easy to transform into nepheline when conditions are available. Stone is difficult to melt, and it is expressed as stone in the finished glass. Therefore, we must pay attention to the difference between K20 and Na2O content. Plant A is in the feldspar of another feldspar source used in the previous year, K20 and Na20.
The content is 6.0-7.0%, the results of use: nepheline in the glass can not be eliminated. Secondly, the index of particle size ≥ 30 mesh is 0, because coarse feldspar, melting is difficult, and it is easy to produce line defects in the glass.
Soda ash: Usually, NaCl <0.3 and fine powder less than 140 mesh ≤ 15% are the main control indicators. Reason: NaCl has a serious erosion on the refractory of the furnace, and the current life of the kiln is very long, generally designed for 10 years. Therefore, the NaCl content is strictly controlled. Secondly, the strict control of the subdivision is because if the fine powder is too much, the amount of scattering will be large, and the frequent variation of the scattering rate will not be considered in the calculation of the general ingredients. Therefore, the change of the large amount of scattering will directly affect the composition and even the glass composition. The changes that affect production. At the same time, too much fine powder, scattered into the small furnace, lattice body, etc., also has an erosion effect on the kiln body.
The above points indicate the main control indicators of the main raw materials, but it does not indicate that other quality indicators can be ignored. This is only to distinguish them from the degree of influence, so as to facilitate the focus in the work. Other non-essential quality control indicators are often given some relaxation in actual implementation, that is, a concession acceptance, or some indicators can be leveled in the batching process, such as CaO, AL2O3, etc. in the composition. It is obviously feasible to have these ingredients in a plurality of raw materials, and to balance them in the seasoning without affecting the glass composition. In view of this, in order to make the raw material quality control more reasonable and more practical, a comprehensive evaluation is required for each raw material.
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