Raw material control methods in glass fiber production
In glass fiber production, raw material control is a key link that determines the quality of the final product, production stability, energy consumption and cost. Slight deviations in glass composition will significantly affect the melting and fiberization processes as well as the physical and chemical properties of the fiber (such as strength, corrosion resistance, electrical insulation, etc.). Therefore, strict and fine control of raw materials is essential.
The following are the main aspects and methods of controlling raw materials:
1. Selection and specifications of raw materials:
Clear composition requirements: According to the type of glass produced (such as E glass, C glass, S glass, AR glass, etc.), formulate precise chemical composition requirements (such as SiO₂, Al₂O₃, CaO, MgO, B₂O₃, Na₂O, K₂O, Fe₂O₃, etc. content range).
Supplier qualifications and evaluation: Select suppliers with good reputation, stable quality, and the ability to provide raw materials that meet specifications. Establish a supplier evaluation system and conduct regular audits.
Strict raw material specifications: Detailed specifications are prepared for each raw material, including:
Main ingredient content range: ensure the provision of the required active ingredients.
Impurity content upper limit: Strictly control harmful impurities, especially:
Sulfides, chlorides, fluorides: affect melting, generate bubbles, and corrode kiln refractory materials.
Heavy metal elements: affect environmental protection and specific applications (such as food contact).
Refractory minerals (such as zircon, corundum): may cause unmelted materials, block the leakage plate holes, and cause wire breakage.
Physical properties: particle size distribution (affects reaction speed, mixing uniformity, transportation and dusting), moisture content (affects batching accuracy), bulk density, fluidity, etc.
Consistency requirements: require suppliers to ensure that the composition and physical properties of different batches of raw materials fluctuate within the allowable range.
2. Receiving and testing raw materials:
Batch management: When each batch of raw materials enters the factory, clearly mark and record the source, batch number, quantity and other information.
Sampling: Sampling is carried out according to scientific and statistically effective sampling methods (such as multi-point sampling and stratified sampling) to ensure that the samples are representative.
Inspection:
Physical inspection: moisture (rapid drying method), particle size (screening, laser particle size analyzer), appearance (color, agglomeration, foreign matter).
Chemical inspection:
Laboratory analysis: Rapid principal component analysis using X-ray fluorescence spectrometer (XRF). For key elements or elements that are difficult to accurately measure by XRF (such as B, F, S, Cl, etc.), wet chemical methods (titration, spectrophotometry, ICP-OES/MS) are used.
Frequency: Key indicators (such as major oxides, key impurities) must be inspected for each batch, and comprehensive analysis is carried out regularly. For raw materials with very stable ingredients, the inspection frequency can be appropriately reduced (such as by supplier batch or fixed cycle).
Release criteria: Only raw materials whose inspection results fully meet the specifications can be put into storage for use. Unqualified raw materials need to be isolated, returned or downgraded (if there is a clear and feasible downgrade use plan).
3. Storage and management of raw materials:
Classification and partition storage: Different raw materials are stored separately to avoid cross contamination. Use dedicated silos or areas. Pay special attention to isolating raw materials that are easily reactive, easy to absorb moisture or easy to volatilize (such as soda ash and sodium sulfate).
Environmental control: The warehouse should be kept dry and well ventilated to prevent raw materials from absorbing moisture and agglomerating (especially soda ash, boric acid, etc.). Control the temperature to avoid decomposition or property changes of certain raw materials.
First in, first out: Strictly implement the principle of first in, first out to prevent long-term backlog of raw materials from causing property changes.
Inventory management: Maintain a reasonable inventory level to ensure continuous production while reducing capital occupation and long-term storage risks. Regular inventory.
4. Precise control of batching process:
Batching calculation: According to the target glass composition and raw material analysis results (especially moisture content), the weighing value of each raw material is accurately calculated. Using special batching software can improve efficiency and accuracy.
Weighing system:
High-precision weighing equipment: Use electronic scales, belt scales or loss-in-weight feeders with high precision (usually requiring an accuracy of ±0.1% or higher).
Calibration and maintenance: Regularly calibrate the scale (using standard weights) to ensure weighing accuracy. Keep the equipment clean to prevent material adhesion or clogging.
Sequence and mixing:
Feeding sequence: Optimizing the feeding sequence can help reduce dust and improve mixing uniformity (for example, raw materials with large volume or large amount of raw materials, then light materials such as soda ash).
Efficient mixing: Use a strong mixer (such as a paddle mixer) to ensure that the batch is highly uniform physically and chemically. Mixing uniformity is a key factor affecting melting quality and homogeneity.
Batch quality inspection:
Uniformity detection: Take samples regularly, analyze the content differences of key components (such as CaO) or tracers (such as adding a small amount of colored sand) in samples at different locations, and evaluate the mixing uniformity.
Moisture detection: Quickly detect the moisture content of the mixed batch.
Particle size detection (if necessary): Check whether there is excessive crushing or agglomeration after mixing.
5. Batch transportation and kiln entry:
Reduce segregation: Use a transportation method that reduces material segregation (such as belt conveyor with plow discharger, reasonable pneumatic conveying design). Avoid long-distance and high-drop transportation.
Avoid stratification: Ensure that the batch remains uniform when entering the kiln feeding port.
Moisture-proof: The conveying system and the kiln head silo should be well sealed to prevent the batch from absorbing moisture and agglomerating.
Summary:
Raw material control for glass fiber production is a systematic project covering the entire process of selection, collection, storage, distribution, delivery, inspection and management. The core lies in:
High-standard raw material specifications and strict factory inspection.
Precise, stable and traceable batching system (the core is weighing accuracy and mixing uniformity).
Scientific batch moisture control and physical state management (reduce dust, segregation, moisture absorption).
Perfect storage management and batch tracking.
Continuous monitoring, analysis and improvement based on data.