A series of articles on the production process of sodium fluosilicate, its preparation, as well as ways to reduce costs and improve raw material utilization in actual production

Part 2 of the series on sodium fluosilicate: (Calculating everything to the core) The requirement for producing sodium fluosilicate from sodium salts is fluorosilicic acid + sodium chloride = sodium fluosilicate. The chemical molecular weight is 144 + 117 = 188. For each ton of sodium fluosilicate product, 0.7659 tons of fluosilicic acid (100%) are required, and 0.622 tons of sodium chloride (100%) are needed. In actual production, to prevent the melting and loss of sodium fluosilicate particles in acidic media, the amount of sodium chloride is increased by 20~30% compared to the original level. Therefore, in actual production, the salt consumption is around 0.75 to 0.809 tons. From the formula above, we can conclude that 1 kilogram of 100% fluorosilicic acid produces 0.1435 kilograms of sodium fluorosilicate ； 100% salt per kilogram can produce 1.236 kilograms of sodium fluosilicate. If 11% fluorosilicic acid and 25% brine are used in production, then 11% of fluorosilicic acid requires 6.96 tons, and 25% brine requires 3.24 tons, for a total of 1 ton of sodium fluorosilicate. At the same time, one can calculate the amount of limestone and lime milk required for wastewater treatment based on the volume of wastewater discharged and the concentration of dilute hydrochloric acid, and determine the cost associated with wastewater treatment by considering the local prices of these materials. In current actual production, people usually set the chemical concentration of sodium chloride at around 25, and that of fluorosilicic acid between 11 and 13, believing that this ratio represents the optimal condition. However, this is not necessarily the case; in fact, it is possible to use brines with a chemical concentration of over 10%, as well as fluorosilicic acid of different concentrations. What matters most are the proportions of these substances as well as their flow rates. Therefore, in order to save water and reduce wastewater discharge, we can absolutely use saltwater with a temperature of over 25 degrees, as well as fluorosilicic acid at temperatures of 30 to 40 degrees! ! ! ! ! ! !

Continuous production of sodium fluosilicate – the entire process, from feeding to the finished product, operates in a continuous manner without interruptions, enabling 24-hour non-stop production. As a by-product in the production processes of phosphate fertilizer manufacturers and hydrofluoric acid producers, fluorosilicic acid is most commonly used in the industry to react with sodium chloride or sodium sulfate to produce sodium fluorosilicate. In recent years, with the development of the fluoride salt industry, there has been a demand that exceeds supply, leading to rising prices year by year. Therefore, how to save costs has become a major challenge for some companies. 1: Analyze costs from the perspective of product raw material selection: The current production process involves using fluorosilicic acid along with sodium chloride or sodium sulfate in specific proportions, through wet or dry methods to produce the product. In recent years, some phosphate fertilizer manufacturers have adopted a process that uses sodium sulfate as the sodium salt for producing sodium fluosilicate. The advantage of this approach is that the wastewater (dilute sulfuric acid) can be reused in earlier stages of the production process, thereby reducing the costs associated with wastewater treatment ； The disadvantages are that the cost of sodium sulfate is higher than that of sodium chloride, and since the precipitation temperature of sodium sulfate in solution is difficult to control, it can cause pipeline blockages… Therefore, for enterprises with large production volumes, the more mature process at present remains the wet-process using sodium chloride. II: Analyzing costs from the perspective of differences in production processes: Many domestic enterprises use the batch production process involving sodium fluosilicate. The disadvantages of this approach are as follows: 1. It imposes a high workload on workers ； 2. The product cannot be produced continuously, resulting in low output ； 3. Insufficient reaction time and uneven stirring lead to localized nucleation, causing the product to appear in a powdery form ； 4. Due to the large contact area of the product, clumping is likely to occur after it is stored for an extended period of time ； 5. Powdered products are difficult to dehydrate; moreover, the high rotation speed of the filter cloth during centrifugal dehydration breaks the product crystals and allows them to pass through the filter pores, resulting in significant loss of product and thus a reduction in yield ； 6. Due to the small size of the product particles, impurities that adhere to the product increase, thereby reducing the purity of the product ； 7. During air-drying, the small size of the particles and high moisture content lead to increased coal consumption ； These problems forced innovative entrepreneurs to turn their attention to the continuous production process for fluorsilicic acid sodium in a sedimentary form! ! III: Advantages of the production process for fluorsilicate sodium in a fluid-sand form: 1. Fully enclosed system – minimal odor during production, which reduces the harm caused by silicon tetrafluoride gas to human health as well as its corrosive effect on the workshop ； 2. The production equipment is corrosion-resistant, as it is made entirely of PP polypropylene, **which reduces the annual maintenance costs associated with corrosion ； 3. The equipment is easy to move and can be installed on-site; no extensive foundation work is required, and it can also be operated in outdoor areas ； 4. Continuous production process, with output capacity that can be designed from 0.7 tons/h to 5 tons/h. 5. Low labor intensity, two shifts per day. 2 people per class are sufficient ； 6. Due to the small contact area between the sand-like sodium fluosilicate particles, they do not clump together when stored under compression ； 7. Flow meters are used for the feed materials in production, and the ratio of salt to acid is strictly controlled to avoid raw material losses resulting from empiricism ； 8. The special stirring structure inside the equipment, along with the appropriate stirring speed, accelerates the rapid precipitation of crystals from the solution, allowing them to grow into relatively large crystals. IV: Selection of reaction equipment for fluorsilicic acid in a sand-like state: Through extensive practical experience, as well as by combining the theories of numerous scholars and professors both domestically and internationally who specialize in sodium fluorsilicate, I have successfully developed the following equipment: 1. A continuous reaction system that allows the time from when the raw materials enter the reaction vessel until the reaction is complete to be controlled at around 1 hour, thereby enabling the product to go through the four stages of crystallization, nucleation, growth, and aging. Ultimately, a uniform Corey structure was formed, with a product diameter within 100 um ； 2. Filtration system: It replaces the traditional method of using centrifuges with a vacuum negative pressure process. Complete the dehydration and washing processes in one go. To address the widespread issues of excessive consumption and low utilization rates in China’s fluoride salt industry, it is hoped that those with a commitment to this cause will engage in extensive exchanges.

The amount of sodium fluosilicate entering the wastewater has reached 2% – what is the main reason for this?

If your dilute sulfuric acid contains sodium ions, it cannot be used to decompose phosphate rocks after concentration, which will affect the normal operation of subsequent processes.

What is the impact of sodium ions on phosphate production?

Hello! The fluorosilicic acid in our company is a by-product of AHF production; to convert it into sodium fluorosilicate, what type of centrifuge should be used? Additionally, due to the strong wind and sand conditions in our area, production takes place in enclosed spaces – how can we get rid of the unpleasant odors?