Study on Vacuum Extraction of Yellow Phosphorus from Mud Phosphorus at Medium Temperature

Exploration and Application-Study on Technology of Extracting Yellow Phosphorus from Mud-phosphorous Medium Temperature Vacuum Liu Yungen Jiang Yingxiang 2 Zhou Ping 1 College of Territorial and Resource Engineering, U-Kunming University of Science and Technology, Kunming 650093, China 2 College of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650093, China) Phosphorus superior product requirements.

Phosphorus is one of the main by-products produced during the yellow phosphorus production process and belongs to hazardous solid waste in the phosphorus chemical industry. The treatment and utilization of mud phosphorus is a very important issue in the production of yellow phosphorus. It not only affects the recovery rate and production cost of phosphorus in industrial production of yellow phosphorus, but also causes serious environmental pollution. Therefore, almost all domestic yellow phosphorus production Manufacturers are all discussing the treatment and utilization of mud and phosphorus in order to achieve good environmental, economic and social benefits so as to realize the strategy of human sustainable development.

1 Status Quo of Phosphorus Extraction from Yellow Phosphorus At present, the main methods for extracting yellow phosphorus from mud and phosphorus in China are: phosphorus evaporation method, chemical reagent method, and vacuum suction filtration method. 11 The most widely introduced foreign methods are electric field treatment method and adsorptive separation method. The following is a brief introduction to these methods.

1 Phosphorus method 131 heats the phosphorous to about 2800C, so that the solid phosphorous in the phosphorous is sublimated to phosphorous vapor, and then the phosphorous vapor is sprayed with water in the condenser to condense it into liquid yellow phosphor to separate the phosphorous and solid impurities. Finally, the qualified yellow phosphorus recovery rate of this method can reach 80%.

Phosphorus evaporation method has the advantages of simple operation, but there are shortcomings such as short life span of phosphatic thorium, serious environmental pollution, low recovery rate of phosphorus, and low economic benefit.

12 Chemical Solvent Method The Chemical Solvent Method 131 uses certain chemical agents to destroy the pectrosome of muddy phosphor to achieve the separation between elemental phosphorus and solid particles. The chemical agent method can also be divided into solvent oxidation method and extraction method.

Regardless of solvent oxidation method or extraction method, the treatment method is simpler and easier to control than simple processes. However, the recovery rate of yellow phosphorus in this method is generally not high, which is about 75%. The content of yellow phosphorus in finished products is relatively high, the level of yellow phosphorus is not high, and the cost of chemical solvents is high. It is easy to corrode the processing equipment and cause some pollution to the environment.

3 Vacuum suction filtration method The vacuum suction filtration method 13 is to suck the mud phosphorus under the heat preservation of 70 ~ 80*C, and in the funnel using the second layer silk cloth as the filter cloth, vacuum suction filtration. The vacuum degree is 53~93324Pa mmHg. The suction filtration time is 5~10min. The yellow phosphorus absorption rate can reach 80%~90%. The purity of yellow phosphorus can reach 99 95%. The filter cake after vacuum suction filtration still contains 20 % ~ 30% of phosphorus, this slag will spontaneously burn in the air, smoke, and pollute the environment.

In view of the above description of the domestic method of extracting yellow phosphorus from the mud and phosphorus, and my understanding of some foreign technologies for extraction of yellow phosphorus from the mud phosphorus, the following conclusions can be drawn: Currently, the method of extracting yellow phosphorus from mud phosphorus has the advantages of simple operation. However, there are problems such as low recovery of phosphorus, low grade of finished phosphorus, high operating costs, and serious environmental pollution. In spite of the advantages of low operating cost, good working conditions, high qualification rate, and good safety performance, foreign mud and phosphorus treatment methods require high material requirements for mud and phosphorus treatment equipment, high initial investment costs, and problems with technology transfer. . In order to further improve the recovery of yellow phosphorus and try to avoid the emergence of the above problems, we proposed here to extract yellow phosphorus in the middle temperature and vacuum method.

2 Phosphorus intermediate temperature vacuum method to extract yellow phosphorus 1 mud phosphorus extraction of yellow phosphorus in the middle temperature vacuum method Overview of the production of yellow phosphorus, mud phosphorus generally have no fixed melting point, the main components of water, yellow phosphorus, arsenic, carbon, Silica, iron oxide and alumina. The process of extracting yellow phosphorus by mud-middle-temperature vacuum method is also a distillation process. It mainly uses the difference in the volatility between water, phosphorous, arsenic and impurities in muddy phosphorus to achieve the separation of the three. Among them, the boiling point of water is the lowest (100*c at a standard atmospheric pressure) and it is volatile group. The higher the boiling point of phosphorus, which is 280*C at a standard atmospheric pressure, is the less volatile component; the highest boiling point of arsenic (460C at a standard atmospheric pressure) is the most difficult component to separate.

22 Phosphorus Intermediate Vacuum Vacuum Extraction Process Yellow Phosphorous Test Procedure According to the current status of the phosphatic treatment and the classification of the distillation process, the yellow phosphorus test of this phosphatic medium temperature treatment is batch distillation, simple distillation, atmospheric distillation and multi-component distillation.

The simple distillation operation of mud phosphorus is a single-stage distillation operation, often performed in an intermittent manner. Phosphorus intermediate temperature extraction yellow phosphorus distillation device schematic shown.

After putting the phosphorus power P into the silo, the outside of the silo is wrapped with electric wire for heating, and the bottom fire is added at the bottom of the silo. In addition, heat-insulating asbestos blankets are added to the heating chamber of the silo and the conduits above the silo to reduce heat loss during the heating process. After the silos are heated in the silo, the water vapor enters the condensing pipe first, and the condensed condensate continuously flows into the receiver as a distillate product. Since the vapor phase composition y is greater than the liquid phase composition x, the composition of the liquid phase in the silo continues to decrease as the process proceeds, making the equilibrium gas phase composition (distillate composition) also decrease at any time, while the liquid in the silo The boiling point gradually increased. When the temperature in the bin exceeds the boiling point of phosphorus, phosphorus gradually evaporates from the mud. With the average composition of the distillate or the residue composition of the silo dropped to a specified value, the distilling operation of the mixed liquid can be stopped. The pressure in the condenser is changed. 1 Phosphorus is due to phosphorite ore, coke silica, etc. In blishing to control burglary, the analysis of the phosphorus butterfly shows that the substance distilled at 280°C to 330°C is mainly phosphorus, while a small amount of arsenic and other impurities with very little content volatilize. This is because the volatile component water has been completely volatilized before the phosphorus is volatilized in a large amount, whereas the carbon, silica, iron oxide and alumina have a very high boiling point and are difficult to evaporate in this temperature range.

Through the continuous improvement and improvement of the test process, the problem of volatilized phosphorous returning to muddy phosphorus, burning muddy mud, and severe heat dissipation when heating is fully avoided. The use of the above principles and process design found during the test: 1 After heating to 300C, large quantities of yellow phosphorus constantly dropped from the condenser into the receiver; 2 After heated to a constant temperature of 300C for a certain period of time, there is no longer Phosphorus is dropped from the condenser into the receiver and a second negative pressure occurs (when the first negative pressure appears in the water in the muddy water), indicating that the yellow phosphorus in the phosphorus is evaporated; 3 After the heating is finished and after it is cooled, the silo is opened and the peat slag in the silo has been observed to be very dry and loose. This shows that this test can well solve the problem of incombustibility of the phosphorous.

23 Phosphorus Intermediate Temperature Vacuum Extraction Yellow Phosphorus Test Results Through the analysis of the evaporated phosphorous slag and finished yellow phosphorus, the following results were obtained: -105% of yellow phosphorus, arsenic content is generally 000032% ~ 0i00185%. After the distillation, the peat slag in the silo was black and loose, indicating that the phosphorous slag contained less phosphorus, and the test solved the problem of incombustibility of the mud phosphorus.

94%, in which the arsenic content is 000958% (see Table 1), the yellow phosphorus grade is excellent, and the industrial yellow phosphorus grade is shown in Table 2 in Table 1. The results of the yellow vacuum distillation of the yellow phosphorus analysis result Table 2 GB78161998 The requirements of the industrial yellow phosphorus project is excellent The appearance of the product is paraffin-like, yellowish paraffin-like yellowish green to yellowish green to brownish green. benzene content in yellow phosphorus CS2 insoluble content in benzene content CS2 content in arsenic taken from the silo, silo exit The residual mud phosphorus at the site is less, only a small amount of yellow phosphorus remains between the re-packing and the silo mouth, which shows that the test is a good solution to the issue of phosphorus reflux.

3 Conclusion Phosphorus intermediate vacuum extraction of yellow phosphorus can extract more than 99% of phosphorus in yellow phosphorus, the proposed yellow phosphorus content of up to 9994%, of which the arsenic content is 0 00958%, to meet the requirements of the national standards of industrial yellow phosphorus This method has a certain ability to remove arsenic, the average removal rate of arsenic is about 17%; two negative pressures appear in the process of phosphorus evaporation, which is helpful to determine the evaporation status of phosphorus and whether the evaporation of phosphorus is completed; There will be no serious environmental pollution during the process. However, due to some sealing problems, a small amount of phosphorus may evaporate out and burn to produce a small amount of white smoke. After the evaporation, the phosphorous slag will not be very low due to the low phosphorus content. Contamination of the environment. In order to achieve the industrialization of the yellow phosphorus method for the vacuum extraction of yellow phosphorus from mud-phosphorus, it is necessary to further improve this test (mainly the improvement of equipment) and expand the test to meet the industrial production.

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