Method for producing high-purity mercury and other low-melting metals

Abstract

FIELD: metallurgy.SUBSTANCE: method for producing high-purity elemental mercury or other low-melting metals. Vacuum is created to ensure the evaporation of mercury or another low-melting metal from the original metal-containing material in a vacuum and the subsequent condensation of its vapors. In this case, the process of evaporation and condensation is carried out in multi-stages in evaporation apparatuses and condensation apparatuses, connected in series by means of intermediate hydraulic seals. The supply of the initial metal-containing material and the removal of the purified metal are carried out through the inlet and outlet hydraulic seals, respectively, filled with the metal being purified. Moreover, the first portion of the obtained purified metal is returned to the beginning of the process.EFFECT: efficiency of purification of mercury and other low-melting metals from impurities is increased.1 cl, 1 dwg

Description

[0001] The present invention is directed to providing a method for producing high-purity elemental mercury.

[0002] The closest to the claimed technical solution is “Installation and method for removing mercury from waste by vacuum distillation” WO 9822628 [1], which includes: - a sealed chamber in which waste can be collected, subjected to elevated temperature and reduced pressure, - a line for removing steam from said chamber, and also - means for cooling the removed steam and collecting condensed mercury, characterized in that the installation includes at least three electrically heated, mobile furnaces that are connected by means of a connecting line and a cooling device to a distillation vessel connected to a vacuum pump.

[0003] The disadvantage of the known solution is the low efficiency of mercury purification.

[0004] Technical result: increasing the efficiency of purification of mercury and other low-melting metals from impurities.

[0005] The technical result is achieved in that the method for producing high-purity mercury or other low-melting metals, including the creation of a vacuum with the provision of evaporation of mercury or another low-melting metal from the initial metal-containing material in a vacuum and the subsequent condensation of its vapors, is characterized in that the process of evaporation and condensation is carried out in multistage stages in evaporation apparatuses and condensation apparatuses, sequentially connected by means of intermediate hydraulic seals, the supply of the initial metal-containing material and the removal of the purified metal are carried out through the inlet and outlet hydraulic seals, respectively, filled with the metal being purified, wherein evaporation is carried out at a temperature of Tisp, and condensation at a temperature of Tcond, at Tcond < Tisp and Tcond > Tpl - the melting temperature of the metal being purified, wherein the first portion of the obtained purified metal is returned to the beginning of the process.

[0006] Implementation:

[0007] The Fig. shows a diagram of the device, where:

[0008] 1. Raw material container

[0009] 2. The first evaporation apparatus.

[0010] 3. Second evaporation apparatus.

[0011] 4. The third evaporation apparatus.

[0012] 5. The fourth evaporation apparatus.

[0013] 6-9. Steam condensation devices with hydraulic seals at the outlets.

[0014] 10. Collection tank for purified material

[0015] 11. Filling device for creating an outlet water seal.

[0016] 12,16. Shut-off valve.

[0017] 13. Container for finished products.

[0018] 14. Turbomolecular pump.

[0019] 15. Vacuum gauge.

[0020] 17. Inlet water seal.

[0021] 18. Outlet water seal.

[0022] 19. Intermediate water seals.

[0023] The device (using mercury as an example) operates as follows:

[0024] The initial (raw) mercury is poured into the receiving tank1, in the volume required to create an inlet water seal 17 from mercury between the receiving tank1 and the first evaporation apparatus2, at the same time, the required amount of mercury is poured through the mercury filling device 11 to create an outlet water seal 18 after the tank 10, the tap 12 is in the closed position. A turbomolecular (or other) vacuum pump in the circuit of apparatuses 2,3,4,5,6,7,8,9,10 creates a vacuum to accelerate the process of mercury evaporation in the evaporation apparatuses and to prevent the process of moisture freezing from the air in the mercury vapor condensation apparatuses. Between the receiving tank 1 and the evaporation apparatus 2, under the influence of the vacuum, an inlet mercury water seal is formed, preventing outside air from entering the installation. The same outlet mercury water seal is also formed after the purified material collection tank 10. After the vacuum is formed in the circuit of apparatuses, valve 16 is closed.In devices 2,3,4,5, the temperature is maintained within T. исп , in mercury vapor condensation devices 6,7,8,9 the temperature is maintained within the range of T конд (T конд below T исп , but above T пл). The temperature regime of evaporation and condensation is specified depending on the design features and the required productivity of a specific installation. The initial mercury is fed into the receiving tank 1 and through the inlet mercury water seal enters the evaporation apparatus 2. As mercury vapor evaporates, it enters the condensation apparatus 6, the mercury condenses and, after filling the corresponding intermediate water seal 19, enters the evaporation apparatus 3. The evaporation-condensation cycle is then repeated in apparatuses 3, 4, 5, 7, 8, 9, 19. With an increase in the number of evaporation-condensation cycles and, accordingly, the amount of equipment required to ensure these processes, the degree of purification of the initial mercury also increases. The composition of the equipment is determined based on the required degree of purity of the final product.The movement of mercury vapor within the unit is ensured by the difference in saturated vapor density at different temperatures. This movement is ensured by positioning the evaporation and condensation units at different elevations. After all buffer cavities are filled, mercury flows into purified material collection tank 10 and subsequently into the transport container when valve 12 is opened. By organizing a continuous mercury feed into the unit, the purification process becomes continuous. It should be noted that the initial portion of mercury, at least the volume used to create the water seal after tank 10 and exiting the unit, is returned to the head of the process. After achieving the required purity parameters, the mercury is loaded into the transport container.

[0025] In addition to mercury, any low-melting metal can be used as a metal to be purified: lead, bismuth, tin, cadmium, thallium, indium, gallium, zinc, etc.

[0026] The evaporation and condensation units can be separated in height with intermediate hydraulic seals between them.

[0027] Height Separation: Uses gravity to naturally move condensed metal from the condenser to the next evaporator, simplifying the design and making the process more energy efficient. Each intermediate water seal between stages further isolates one purification stage from the next, preventing backflow of vapor or liquid and ensuring strict material flow sequence, which is crucial for a multi-stage process.

[0028] Internal surfaces in contact with the metal or its vapors can be made of a material that is chemically inert to the metal being cleaned, preferably stainless steel or glass.

[0029] This design prevents secondary contamination. Guaranteed purity: glass and stainless steel do not release foreign ions or particles into the metal, which is crucial for obtaining "high-purity" metal.

[0030] The technical result of increasing the efficiency of metal cleaning is achieved by: Multi-stage implementation of the evaporation and condensation process in multi-stages in series-connected evaporation apparatuses and condensation apparatuses, series-connected by means of intermediate hydraulic seals.

[0031] Impact: This is the key feature defining the essence of the invention. Instead of a single distillation, as in the prototype, the metal undergoes several evaporation-condensation cycles. Each cycle removes a new batch of impurities that have a different boiling point or do not evaporate at all. The more stages, the higher the degree of purification of the final product. This directly addresses the problem of increasing purification efficiency.

[0032] Feeding the initial liquid metal and removing the purified metal through hydraulic seals: Hydraulic seals create a physical barrier made of the metal itself, preventing outside air from entering the sealed system under vacuum. This is critical because: Air can oxidize the metal or introduce new contaminants, and a breach in the vacuum will reduce the efficiency and speed of evaporation. It ensures safety by preventing the release of metal vapors into the atmosphere.

[0033] Evaporation temperature (T исп): The temperature range for mercury evaporation at normal pressure varies from -38.87 °C (melting point) to +356.7 °C (boiling point); in a vacuum, according to experimental data [Wolmer, Estermann, 1921], mercury begins to evaporate at -64 °C. Reducing the evaporation temperature negatively affects the rate of the process, but prevents the sublimation of impurities contained in black mercury and makes the technology less energy-intensive. The compromise in determining the evaporation temperature is determined by the technical requirements for the final product, namely, the degree of purification and the demand for it.

[0034] Condensation temperature (T конд ): A low condensation temperature ensures complete condensation: the metal vapor almost completely transforms into a liquid phase, minimizing product loss. The condensation temperature must be above the melting point to maintain the unit's functionality, including the patency of the hydraulic seals.

[0035] Returning the first portion of cleaned metal to the beginning of the process: This feature solves the problem of a "contaminated start." The first portion of metal passing through the system may contain residual air, moisture, or impurities remaining in the pipelines and equipment from assembly or a previous run. Returning this portion to the beginning:

[0036] Allows you to "flush" the system with clean metal before starting the main cleaning cycle.

[0037] Ensures that only metal that has undergone a full cleaning cycle after the process has stabilized gets into the final product.

[0038] Improves the stability and predictability of the final product quality.

[0039] Thus, each feature of the invention formula makes a specific and necessary contribution to the solution of the main problem - increasing the efficiency of metal cleaning - by increasing the degree of cleaning, ensuring process safety, preventing secondary pollution and creating a stable, controlled technological cycle.

[0040] Industrial applicability.

[0041] The proposed method for purifying low-melting metals has high industrial applicability and can be successfully implemented in various industries where it is necessary to obtain high-purity elemental metal.

[0042] Main application areas:

[0043] Mining and metallurgy industry: It can be used for the purification of low-melting metals obtained from the processing of ores or concentrates containing metals, and for the recovery of mercury used in technological processes (such as amalgamation).

[0044] Chemical and pharmaceutical industry: High-purity metal is a critical reagent and material for the production of specialty chemicals, catalysts and drugs.

[0045] Research institutions and laboratories: To conduct precise experiments and calibrate equipment, high-purity metal is required, which can be obtained using this method.

[0046] High-tech product manufacturing: Electronics, instrument making and special alloy production may also require high-purity low-melting metal or mercury.

[0047] Advantages for industrial implementation:

[0048] Modularity and scalability: the design of the unit, built on the cascade principle, allows you to easily increase the capacity or degree of purification by adding additional evaporation-condensation stages.

[0049] Continuous operation mode: As stated in the description, by organizing the continuous supply of raw material, the cleaning process also becomes continuous, which increases productivity and reduces the cost of the product.

[0050] Safety: The use of water seals and vacuum operation completely eliminates the release of metal vapors into the atmosphere, making the process environmentally safe and compliant with strict sanitary standards.

[0051] Energy Efficient: The process for mercury or other low-melting metal is carried out at relatively low temperatures, which reduces energy consumption compared to traditional distillation at atmospheric pressure.

[0052] Thus, the proposed method is a technologically advanced, safe and cost-effective solution that can be widely applied in industrial enterprises for waste recycling and obtaining high-quality products.

Claims

A method for producing high-purity mercury or other low-melting metals, including the creation of a vacuum to ensure the evaporation of mercury or another low-melting metal from a source metal-containing material in a vacuum and the subsequent condensation of its vapors, characterized in that the evaporation and condensation process is carried out in multistage stages in evaporation apparatuses and condensation apparatuses, sequentially connected by means of intermediate hydraulic seals, the supply of the source metal-containing material and the removal of the purified metal are carried out through inlet and outlet hydraulic seals, respectively, filled with the metal being purified, while evaporation is carried out at a temperature of Tsp, and condensation - at a temperature of T конд , at T конд < T исп and T конд >T пл – the melting temperature of the metal being purified, with the first portion of the resulting purified metal being returned to the beginning of the process.

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