Silica Fume powder is essentially a “by-product” or “waste product” of the smelting process, not through deliberate production and processing, so its quality will be more subject to the influence of external factors. In order to make the product quality relatively stable, we have done a lot of exploration and research, and come up with a set of effective quality control methods mainly as follows.
Quality Control of Generating Source.
The choice of furnace size: The size of the furnace determines the stability of product quality. Too small furnace, furnace conditions change more frequently, resulting in unstable quality of SiO2, while a furnace larger than 12,500KVA, the output is less, can not ensure the continuity of product supply, therefore, 6300KVA to 12,500KVA industrial silicon furnace is preferred, can ensure that the engineering silica fume powder SiO2 content ≥ 85% and the corresponding impurity content is less, all indicators can meet the relevant standards.
The smelting furnace load size, ore raw material origin quality, reducing agent category and other factors of the mineral heat furnace itself will be initially classified, and the silica fume powder samples will be collected for analysis, and the product classification will be made according to the laboratory results.
Quality Control of Production Process
- In the field of automatic control of the silica fume powder “production line” (environmental protection equipment), through observation of the on-site furnace conditions and communication with the technical personnel in the plant, the main fan control parameters are adjusted to change the air speed at all levels for different furnace conditions and to change the pressure difference between the inside and outside of the filter bag to control the filtration effect without affecting the effect of the environmental protection dust removal equipment, so as to the purpose of adjusting the silica fume content and other parameters.
- In addition, it is also possible to upgrade the dust collection equipment, add temperature-regulated air catcher sets, expand the filtering area of the bag filter, etc., to change the entire dust collection system SiO2 condensation time, molding properties, etc., and finally the parameters of the silica fume powder can be adjusted and controlled within a certain range.
- Before the product is unloaded and sealed, the operator must visually inspect the bag to ensure that the color of the silica fume powder is uniform and the product is free of lumps, and a quality card with a unique number is sewn onto the bag. This makes each bag of silica fume powder traceable, strengthens the operator’s responsibility, and also facilitates the identification of each link of production and storage, which greatly enhances the quality assurance of the product.
The inspection of the production site is an important part of the quality control process. Dedicated site inspection personnel will conduct daily routine inspection of the material yard and smelting site records to ensure that the smelting process, raw materials and finished products have not changed to ensure the stable quality of silica fume powder products. If there are changes in the process, raw materials, furnace conditions and other conditions that may affect the quality of the silica fume powder, the products of the day should be stored differently and the samples should be analyzed in a timely manner and then classified according to the laboratory results.
Quality Control of Products Leaving and Entering the Warehouse.
When the products are stacked in the warehouse, the products of different furnace types shall be sorted and stacked; the products of the same equipment shall be stacked separately as a batch of products produced within a week. The storekeeper shall make records of the origin and stacking location of different batches of products. The laboratory personnel shall take a whole truck (25-30 tons) as a batch and then conduct a sampling inspection, the number of samples shall not be less than twenty bags, the weight of each bag shall not be less than 100g, and the samples shall be mixed evenly and sent for inspection. Each inspection is required to record the test time, index data and other relevant information.