Sodium silicate（HLNAP-2）

When Modulus (M): 2.4±0.1powdered sodium silicate adopts dry process, what is the optimal range of melting temperature and reaction time?

1. Overview of dry process of powdered sodium silicate

(I) Basic principle of dry process
The dry process of powdered sodium silicate is to make liquid water glass into powdered products through drying, spraying and other processes. Its core reaction process involves the melting and solidification of sodium silicate. In the dry process, quartz sand (main component SiO₂) and sodium salts such as soda ash (Na₂CO₃) or caustic soda (NaOH) melt at high temperature to generate sodium silicate melt, and then obtain powdered products through cooling, crushing and other steps.
(II) Key influencing factors of dry process
The core of dry process lies in the melting stage. The temperature and reaction time of this stage directly affect the quality, performance and production efficiency of the product. The melting temperature determines the activation energy and reaction rate of the reactants. If the temperature is too low, the reaction may be incomplete, and the resulting sodium silicate melt may contain unreacted quartz sand particles, affecting the purity of the product and the accuracy of the modulus. If the temperature is too high, it will increase energy consumption, aggravate equipment corrosion, and may even cause excessive polymerization of the sodium silicate melt, affecting the solubility of the product. The reaction time is closely related to the completeness of the reaction and the uniformity of the melt. If the time is too short, the reaction is insufficient and the modulus is unstable. If the time is too long, it will not only reduce production efficiency, but may also cause side reactions and affect product quality. Therefore, optimizing the melting temperature and reaction time is a key link in the dry process.

2. Characteristics and application of powdered sodium silicate with a modulus of 2.4±0.1

(I) Product characteristics
Take the powdered water glass (model HLNAP-2, modulus 2.4±0.1) produced by Tongxiang Hengli Chemical Co., Ltd as an example. This product is made of liquid water glass by drying and spraying, and has significant advantages over liquid water glass. In terms of physical properties, its silicon dioxide content (SiO₂) is 54.0 - 58.0%, Na₂O content is 24.0 - 27.5%, bulk density is 0.65 Kg/L, dissolution rate is ≤60 S/30℃, and particle size 100 mesh pass rate is ≥95%. These indicators show that the product has the characteristics of high content, low moisture, easy transportation and storage, saving packaging and transportation costs, and can be quickly dissolved and used on site. In terms of chemical properties, sodium silicate with a modulus of 2.4±0.1 has moderate alkalinity. After dissolving in water, it can form a stable silicate solution and react with a variety of substances, laying the foundation for its application in different fields.
(II) Application fields
The product is widely used in detergents, cement quick-drying additives, industrial plugging, high temperature resistant binders and other fields. In the detergent industry, powdered sodium silicate can be used as a detergent to enhance the decontamination ability of detergents, adjust the pH value of the solution, and soften water; in cement production, as a quick-drying additive, it can accelerate the coagulation and hardening process of cement and improve its early strength; in the field of industrial plugging, it can be used to repair leaks in pipelines and equipment by utilizing its rapid dissolution and gelling properties; in terms of high-temperature resistant binders, it can be used for bonding and fixing parts in high-temperature environments by virtue of its high-temperature resistance and bonding ability.

3. Optimization range of melting temperature in dry process

(I) Effect of melting temperature on product quality
Effect on modulus: Modulus is a key indicator of powdered sodium silicate, which directly reflects the ratio of silicon dioxide to sodium oxide in the product. In the dry process, the melting temperature affects the equilibrium of the reaction and the composition of the product. When the temperature is low, the reaction rate is slow, and the reaction of silica and sodium oxide is incomplete, which may lead to a low modulus and fail to meet the requirement of 2.4±0.1; as the temperature rises, the reaction rate accelerates, the reaction is more complete, and the modulus gradually approaches the target value, but when the temperature is too high, the sodium silicate melt may be over-polymerized, and the effective content of silica is relatively reduced, causing the modulus to fluctuate.
Impact on solubility: Too high a melting temperature will make the structure of the sodium silicate melt tighter, forming a larger molecular chain, resulting in a slower dissolution rate of the product. For example, when the temperature exceeds 1400℃, some sodium silicate may form a difficult-to-dissolve glass body, causing the dissolution rate to exceed 60 S/30℃, which cannot meet the product index requirements; when the temperature is too low, the melt contains incompletely reacted quartz sand particles, which not only affect the purity of the product, but also hinder the dissolution process and reduce the dissolution rate.
Impact on energy consumption and equipment: Increasing the melting temperature requires more energy consumption and increases production costs. At the same time, a high temperature environment will aggravate the corrosion and wear of equipment and shorten the service life of the equipment. For example, at temperatures above 1300℃, ordinary refractory materials will be severely corroded and need to be replaced frequently, increasing maintenance costs and the risk of production interruption.
(II) Determination of the optimal range of melting temperature
A large number of experimental studies and production practices have shown that for the dry production process of powdered sodium silicate with a modulus of 2.4±0.1, the optimal range of melting temperature is usually between 1250-1350℃. In this temperature range, it can ensure that quartz sand and sodium salt react fully to generate a sodium silicate melt with a stable modulus, while taking into account both solubility performance and production efficiency.
Low temperature range (1250-1300℃): In this temperature range, the reaction rate is moderate, the energy consumption is relatively low, and the degree of equipment corrosion is relatively light. Experimental data show that when the temperature is 1280℃, the modulus of the sodium silicate melt generated by the reaction is 2.38, close to the target value of 2.4, and the dissolution rate is 55 S/30℃, which meets the product index requirements. At this time, the conversion rate of quartz sand can reach more than 95%, and there are fewer unreacted quartz sand particles in the product, with higher purity.
Medium temperature range (1300 - 1330℃): It is a more ideal melting temperature range. When the temperature is 1320℃, the reaction is fully carried out, the modulus is stable in the range of 2.4±0.1, and the dissolution rate is 50 S/30℃, reaching the best state. At the same time, the uniformity of the melt is good, which is conducive to the subsequent drying and spraying process. The powdered product produced has a uniform particle size distribution, and the 100 mesh pass rate can reach more than 98%.
High temperature range (1330 - 1350℃): Although the reaction speed is faster, the energy consumption increases significantly and the equipment corrosion is aggravated. When the temperature reaches 1350℃, the modulus may increase slightly to 2.45, exceeding the upper limit of the target range, and the dissolution rate drops to 65 S/30℃, which does not meet the product requirements. Therefore, in actual production, long-term operation in the high temperature range should be avoided as much as possible.

4. Optimization range of reaction time in dry process

(I) Effect of reaction time on product quality
Influence on completeness of reaction: If the reaction time is too short, the reaction between quartz sand and sodium salt is not sufficient, which will result in more unreacted raw materials in the product, affecting the accuracy of modulus and product purity. For example, when the reaction time is only 30 minutes, the conversion rate of quartz sand is only about 80%, the SiO₂ content in the product is less than 54%, the Na₂O content is higher than 27.5%, and the modulus is as low as about 2.2; as the reaction time increases, the conversion rate gradually increases. When the time reaches 60 minutes, the conversion rate can reach more than 98%, and various indicators are close to the target value.
Influence on melt uniformity: Insufficient reaction time will cause uneven distribution of components in the melt, and the local modulus may be high or low, affecting the stability of the product. Microscopic observation found that there were obvious quartz sand particles and sodium salt aggregation areas in the melt with short reaction time, while the melt with long reaction time had uniform texture and no obvious impurities.
Impact on production efficiency: Too long reaction time will reduce production efficiency and increase production costs. In industrial production, for every 10 minutes of reaction time extension, the unit time output will decrease by about 5%, and energy consumption will increase accordingly. Therefore, it is necessary to reasonably shorten the reaction time while ensuring product quality.
(II) Determination of the optimal range of reaction time
Taking into account the completeness of the reaction, melt uniformity and production efficiency, the optimal range of reaction time for the dry production process of powdered sodium silicate with a modulus of 2.4±0.1 is usually 45-60 minutes.
Short time interval (45-50 minutes): During this time period, the reaction basically reaches equilibrium, the quartz sand conversion rate can reach more than 95%, and the modulus is stable between 2.35-2.45, meeting the requirement of 2.4±0.1. For example, when the reaction time is 48 minutes, all product indicators meet the standards, and the production efficiency is high, and the unit time output is about 8% higher than the 60-minute reaction time.
Medium time interval (50 - 55 minutes): It is an ideal reaction time range. At this time, the reaction is sufficient and uniform, the melt quality is the best, and the powdered product produced has a fast dissolution rate and uniform particle size. Experimental data show that when the reaction time is 53 minutes, the dissolution rate is 52 S/30℃, the 100 mesh pass rate is 97%, and the energy consumption and equipment loss are within a reasonable range.
Long time interval (55 - 60 minutes): Although the reaction is more complete, the production efficiency decreases significantly. When the time reaches 60 minutes, the conversion rate is only about 2% higher than that of 50 minutes, and the output is reduced by about 10%. Therefore, in actual production, unless there are special high requirements for product purity, too long reaction time is generally not used.

5. Production practice and technological innovation of Tongxiang Hengli Chemical Co., Ltd

Tongxiang Hengli Chemical Co., Ltd always pays attention to process optimization and technological innovation in the production process of inorganic silicon products. For the dry production process of powdered sodium silicate with a modulus of 2.4±0.1, the company has introduced advanced testing equipment, such as X-ray diffractometer (XRD), scanning electron microscope (SEM), etc., to monitor the material structure and composition in real time during the melting process, providing a scientific basis for process optimization. Through continuous exploration, the company's R&D team has developed a new type of composite catalyst, which can accelerate the reaction rate and shorten the reaction time by about 10-15% without significantly increasing the melting temperature, while increasing the conversion rate of quartz sand to more than 99%, further improving product quality and production efficiency.
In addition, Tongxiang Hengli Chemical Co., Ltd has also established a complete quality management system to strictly control every link in the production process. From raw material procurement to product delivery, multiple inspection processes are carried out to ensure that the product indicators are stable and reliable. With its professional technical capabilities and high-quality product services, the company has won wide market recognition in many fields such as electronics, clothing, papermaking, agriculture, etc., and its products are sold at home and abroad.