A method for recovering germanium from low acidity distillation residue containing germanium by surfactant enhanced leaching

Abstract

The present application belongs to the technical field of germanium material preparation, and particularly relates to a method for recovering germanium in neutralized residue containing germanium by slow distillation under low acidity with surfactant reinforcement, and specifically comprises the following steps: after waste acid is neutralized with lime after first distillation, the cake is formed by pressure filtration, and the neutralized residue is formed; the neutralized residue with a germanium content higher than 0.4% is screened for standby; manganese dioxide is added according to 3 times to 5 times of the total mass of germanium metal in the neutralized residue obtained by calculation, industrial hydrochloric acid is added according to a mass-volume ratio of the neutralized residue and hydrochloric acid of 1:1 to 3, and the reaction is preheated at low temperature for 1.5 hours to 2.5 hours; the temperature of the distillation reaction kettle is controlled at 45 DEG C to 65 DEG C, the pressure in the reaction kettle is controlled between 10 kpa to 15 kpa, etc.; the germanium in the neutralized residue is separated and extracted by slow distillation under low acidity in the second distillation, and the direct recovery rate can reach 90%, and the recovery rate can reach 93%.

Description

Technical Field

[0001] This invention belongs to the field of germanium material preparation technology, specifically relating to a method for recovering germanium from germanium-containing neutralized residue by leaching with surfactant-enhanced low-acidity distillation, namely, a method for recovering and extracting germanium from the filter cake after neutralization and pressure filtration of germanium-containing waste acid by secondary low-acidity chlorination distillation. Background Technology

[0002] In the chlorination distillation process of germanium, the impurities in the germanium-containing raw materials are complex and varied. The chlorination section generally uses chlorination distillation, where the solid-liquid ratio of germanium concentrate to hydrochloric acid in the reactor is approximately 1:6 to 1:10, and the solution temperature is 100℃-110℃. However, due to the reversible reaction GeCl4 + H2O → GeO2 + HCl inherent in the chlorination distillation process, the acidity is below 6. At concentrations of mol / L, the reversible reaction becomes more pronounced. Furthermore, some germanium exists in different forms or has different crystal structures, resulting in a high germanium content in the waste acid after primary chlorination distillation. This is especially true when the distillation rate is low, leading to a greater amount of residual germanium in the waste acid. This germanium mixes with the waste acid solution, and after neutralization, the germanium content in the neutralization residue ranges from 0.05% to 1.50%. Failure to recover this germanium would result in a waste of germanium resources. Practical experience has shown that the germanium in this neutralization residue is very difficult to distill off during primary distillation. If the conventional chlorination distillation method for germanium concentrate is simply followed, there are significant reactions during acid addition. After acid addition, no germanium is collected in the storage bottle during distillation; only a very small amount is recovered in the alkaline solution. The germanium in the alkaline solution still needs to be recovered through further chlorination distillation, resulting in a low germanium recovery rate and difficulty in completely distilling off the germanium from the waste acid neutralization residue.

[0003] Before the application of this technology, the main method for treating neutralization slag was to neutralize the waste acid after chlorination distillation with lime, store it in a slag storage facility, and then transport it to a qualified hazardous waste disposal unit for disposal. This disposal method resulted in: 1) a waste of germanium resources; 2) an increase in the extraction and purification production costs of germanium; and 3) a significant increase in transportation and handling costs. Summary of the Invention

[0004] This invention addresses the problems of germanium loss and high recovery costs in germanium-containing neutralization slag generated after the waste acid produced by chlorination distillation of germanium-containing raw materials is neutralized with lime. It provides a method for recovering germanium from germanium-containing neutralization slag by enhancing leaching with surfactants and low-acidity distillation, thereby achieving high-efficiency and low-cost recovery of germanium metal from germanium-containing neutralization slag.

[0005] The specific implementation technical solution is as follows:

[0006] A method for recovering germanium from germanium-containing neutralized residue by enhancing leaching with surfactants using low-acidity distillation includes the following steps:

[0007] The waste acid after the first distillation of S1 is neutralized with lime and then pressed into cakes by a filter press for later use.

[0008] S2 will analyze the germanium content of the neutralized residue filter cake produced and screen the neutralized residue with a germanium content higher than 0.4% for later use.

[0009] S3 feeding: The prepared neutralization residue is fed into the chlorination distillation reactor, and then manganese dioxide is added at 3 to 5 times the calculated amount of germanium metal in the neutralization residue. The tail gas system of the reactor is turned off, the solid feeding port is closed, and industrial hydrochloric acid is added at a mass-volume ratio of neutralization residue to hydrochloric acid of 1:1 to 3, wherein the concentration of the industrial hydrochloric acid is 10 mol / L.

[0010] S4 Low-temperature pre-reaction 1.5h~2.5h: The temperature of the distillation reactor is controlled at 45℃~65℃, and the pressure inside the reactor is controlled between 10kpa~15kpa; according to the mass-volume ratio of the amount of neutralized residue to the surfactant, a surfactant with a mass-volume concentration of 100g / L is added to increase the pre-reaction effect. The surfactant is sodium dodecylbenzenesulfonate.

[0011] S5 heating and distillation, the pressure inside the reactor is reduced to 4 kPa, the pre-reacted material is heated to 110℃, and acid is added in small amounts and multiple times to control the acidity of chlorination distillation in the reactor to 4 mol / L~5.5 mol / L;

[0012] S6 The waste liquid obtained after extracting germanium from the germanium-containing lime neutralization residue through secondary distillation is then neutralized with lime to form germanium-free neutralization residue, which is then stored in a slag silo for transfer.

[0013] The principle of this invention is that, during the pretreatment of germanium-containing neutralization slag, an anionic surfactant sodium dodecylbenzenesulfonate is added along with industrial hydrochloric acid. Due to its strong anionic dispersing effect, chlorides and other salts in the neutralization slag are easily dissolved by the industrial hydrochloric acid under acidic conditions. This allows germanium ions and germanium metal, which are encapsulated by calcium chloride, hydroxides, and ferric hydroxide, to be fully released, forming Ge... 4+ When ions enter the solution, the metallic germanium is oxidized to form Ge. 4+ The method involves two main approaches. First, ions enter the solution and escape as GeCl4 during distillation, thus achieving separation and extraction. Second, the neutralization residue filter cake produced after neutralization contains a large amount of chloride, which forms chloride ions after being dissolved by acidification. Due to the common ion effect, germanium tetrachloride is vaporized and escaped at a lower temperature, thereby achieving separation and extraction of germanium and realizing distillation recovery of germanium at a lower acidity.

[0014] The addition of the anionic surfactant sodium dodecyl sulfonate serves two main purposes: first, emulsification and dissolution, enabling the acid to wet and neutralize the residue. Because some recycled germanium raw materials contain grease, and grease has high surface tension in water, it is not easily wetted by acid. When the grease in the solution is broken into fine beads, they mix together to form an emulsion, but the layers separate again after stirring stops. Adding the surfactant and stirring allows it to act around the encapsulated germanium, promoting the reaction between germanium and chlorine. The second function of the surfactant is dispersion, breaking down the solid particles in the reactor into smaller particles, dispersing and suspending these easily aggregated solid particles in the solution, making them more readily involved in the reaction.

[0015] This invention addresses the issue of germanium in different forms that failed to distill during primary chlorination distillation. By setting a higher pressure than conventional chlorination distillation during a low-temperature pre-reaction process, the chlorination reaction in the reactor is enhanced, allowing germanium that was not chlorinated during primary distillation to be distilled out by the system and then condensed and collected.

[0016] The technical effects achieved by this invention are as follows:

[0017] 1. The application of this invention increases the utilization rate of germanium resources and reduces the waste of germanium resources. The germanium in the waste residue that originally needed to be entrusted to other solid waste treatment companies can be directly recovered after secondary distillation.

[0018] 2. The hydrochloric acid consumption of this invention is about half that of conventional distillation methods (the acidity during conventional distillation is 6.8 mol / L to 7.5 mol / L). Moreover, the germanium-containing neutralization residue is transferred to other environmental protection companies for treatment as solid waste, with a unit price of about RMB 1 to 1.5 per gram. However, the germanium tetrachloride produced by low-acidity distillation can be further processed to increase its unit price to RMB 8.5 to 10 per gram. According to the company's existing production process, the company's overall recovery rate can be increased by about 0.5% to 1%, generating a profit of about RMB 700,000 to 1.8 million per year for the company.

[0019] 3. Provide methods and basis for using chloride salts to reduce distillation acidity in germanium smelting processes, providing support for the improvement of germanium metallurgical technology, especially in terms of resource conservation.

[0020] After secondary distillation, the germanium content in the germanium-containing neutralization residue is as low as 0.01% to 0.2%, and the germanium distillation rate can reach more than 90%, which improves the germanium recovery rate, reduces production costs, and improves the comprehensive utilization efficiency of germanium resources. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0022] Example 1

[0023] After the first distillation of S1, the waste acid is neutralized with lime until the pH of the neutralized solution is 7-9. When the germanium content in the waste acid is found to be less than 5 mg / L, it is filtered into cakes by a filter press for later use. The liquid enters the production water treatment system for purification.

[0024] After S2 analysis, the samples were sorted and stacked. The neutralized residue filter cake was analyzed to determine its germanium content. It was then spread out and dried for 15 days. Neutralized residue with a germanium content higher than 0.4% was stacked separately for later use, while the rest was stored in the warehouse.

[0025] For S3 feeding, add the prepared neutralization slag into the chlorination reactor, then add manganese powder at a ratio of 3 to 5 times the calculated total amount of germanium metal in the neutralization slag. Close the solid feed port and shut off the reactor's tail gas system. Slowly add industrial hydrochloric acid (10 mol / L) at a solid-liquid ratio of neutralization slag to hydrochloric acid of 1:1 to 3 (flow rate: 20 L / min). After adding hydrochloric acid, the reaction between manganese dioxide and hydrochloric acid is as follows:

[0026] 4HCl (conc.) + MnO2 = MnCl2 + Cl2↑ + 2H2O

[0027] When hydrochloric acid is added, the neutralization residue contains a small amount of alkalinity, which will cause an acid-base neutralization reaction that releases a certain amount of heat, increasing the heat inside the reactor. At the same time, the generation of chlorine gas increases the pressure inside the reactor.

[0028] S4 low-temperature pre-reaction 1.5h~2.5h: Control the temperature of the distillation reactor at 45℃~65℃ and closely observe the reaction. The pressure inside the reactor must not exceed 15kPa or be lower than 10kPa. If the pressure is too high, stop stirring and heating. Alternatively, water cooling can be turned on to lower the temperature. If the pressure is lower than the limit, start stirring or increase the temperature.

[0029] If the distillation temperature and acidity are not reached, the hydrochloric acid in the system reacts with manganese dioxide, increasing the amount of chlorine in the sealed system and the pressure in the reactor is also high. At this time, the main reaction taking place in the chlorination distillation reactor is the reaction of unreacted metallic germanium from the first distillation with chlorine:

[0030] Ge + 2Cl₂ = GeCl₄

[0031] During the above operation, the partially oxidized germanium encased in the reactor undergoes slow chlorination in a high-pressure chlorine atmosphere, thus forming germanium tetrachloride.

[0032] Add a surfactant at a concentration of 100 g / L according to the mass-volume ratio of the neutralization residue to the surfactant solution of 10:1-10:3 to enhance the pre-reaction effect;

[0033] S5 heating and distillation: As the reaction in the reactor gradually slows down and the pressure in the reactor drops to about 4 kPa, the fully pre-reacted material is heated to 110°C. Hydrochloric acid, 1-2 times the mass of the neutralization residue, is added to start low-acidity chlorination distillation. The specific amount of acid added is calculated based on the acid concentration in the reactor. If the calculated acidity in the reactor is 4 mol / L, acid is added and distillation begins. Depending on the amount of germanium tetrachloride produced, acid is added in small amounts multiple times to ensure that the final acidity in the reactor does not exceed 5.5 mol / L.

[0034] During the gradually increasing temperature distillation process, germanium ions in the reaction vessel combine with chloride ions to form germanium tetrachloride. After distillation and vaporization, the tetrachloride is released and collected by condensation, thus achieving the purpose of extracting germanium. The reaction process is as follows:

[0035] Ge 4+ +4Cl — ===GeCl4↑

[0036] The principle of low-acidity distillation is that because the neutralization residue contains a large amount of chloride ions, there are sufficient chloride ions in the reaction vessel at this time, which inhibits the hydrolysis reaction of germanium tetrachloride.

[0037] S6 secondary distillation waste acid containing germanium is neutralized with lime and then placed in a slag storage facility for transfer.

[0038] Example 2

[0039] After the first distillation of S1, the waste acid is neutralized with lime until the pH of the neutralized solution is 7-9. The germanium content is tested to be less than 5 mg / L. The solution is then filtered into a cake using a filter press, and a sample is taken for chemical analysis of its germanium content. The liquid then enters the production water treatment system for purification.

[0040] After S2 analysis, the residue was sorted and stacked. The neutralization residue with a germanium content higher than 0.4% was stacked separately, spread out and dried for 15 days before use, while the other neutralization residue with a germanium content lower than 0.4% was stored in the warehouse.

[0041] In step S3, 500 kg of the neutralization residue prepared in step S2 is added into the chlorination reactor. The residue is found to contain 20.01% water and 1.05% germanium. The amount of germanium metal added is approximately 5.040 kg. At the same time, 25.20 kg of manganese powder is added. The solid feed port is closed, and the tail gas system of the reactor is shut off. 500 L of hydrochloric acid is added at a solid-liquid ratio of 1:1 over 50 minutes at a flow rate of 20 L / min.

[0042] S4 Low-Temperature Pre-Reaction 2h: Turn on the temperature control system and set the temperature to 50℃. Control the temperature of the distillation reactor at around 50℃ and closely observe the reaction. The pressure inside the reactor must not exceed 15kPa or fall below 10kPa. If the pressure is too high, stop stirring and heating. Alternatively, water cooling can be used to lower the temperature. If the pressure is below the limit, turn on stirring or increase the temperature. Add 50L of surfactant with a concentration of 100g / L at a ratio of 10:1 (raw material to surfactant solution) to enhance the pre-reaction effect.

[0043] After the S5 heating distillation process and low-temperature pre-reaction, the pressure inside the reactor drops to about 4 kPa. The fully pre-reacted material is then heated to 110 degrees Celsius, and 1-2 times the amount of hydrochloric acid is added to begin low-acidity heating and chlorination distillation. Acid is added in small amounts multiple times to ensure that the final acidity inside the reactor does not exceed 5.5 mol / L and is not lower than 4 mol / L.

[0044] Turn on the stirrer to mix the materials in the reactor evenly and begin the reaction. A small amount of hydrochloric acid and crude germanium tetrachloride can initially be collected in the storage bottle. Continue heating for about 1 hour, and 7L of liquid crude germanium tetrachloride, containing 4.461kg of germanium metal, is collected in the collection bottle. In the tail gas absorption tower, 25kg of sodium hydroxide is added to a 500L alkaline tail gas absorption tower, slightly increasing the germanium content in the alkaline solution by 0.3g / L, recovering 0.15kg of germanium. This indicates that when recovering germanium from the neutralization residue according to the solid-liquid ratio of this invention, the reaction rate is well controlled, the distillation effect is good, the reaction is complete, the direct recovery rate is 88.51%, and the overall recovery rate can reach 91.50%.

[0045] Comparative Example 1

[0046] After the first distillation of S1, the waste acid is neutralized with lime until the pH of the neutralized solution is 7-9. If the germanium content is found to be less than 5 mg / L, it can be filtered by pressure. The filter cake is then sampled and chemically analyzed for its germanium content. The liquid then enters the production water treatment system for purification.

[0047] After S2 analysis, the residue was sorted and stacked. The neutralization residue with a germanium content higher than 0.4% was stacked separately, spread out and dried for 15 days before use. The other neutralization residue with a germanium content lower than 0.4% was stored in the warehouse.

[0048] In step S3, 500 kg of the neutralization slag prepared in step S2 is added to the chlorination reactor. The slag contains 20.12% water and 1.0% germanium. The amount of germanium metal added in this batch is approximately 3.994 kg. Then, 19.97 kg of manganese powder is added, which is 5 times the total amount of germanium metal in the neutralization slag. The tail gas system of the reactor is shut off. 3000 L of industrial hydrochloric acid (10 mol / L) is slowly added at a solid-liquid ratio of 1:6, and the addition is completed in 0.5 h. The flow rate of hydrochloric acid is 100 L / min. If the reaction is violent during the acid addition process and the pressure in the reactor exceeds 15 kPa, the acid addition rate is reduced to 50 L / min to ensure safety, or the tail gas is opened to release the pressure.

[0049] S4 heating distillation: After the first addition of hydrochloric acid, the pressure inside the reactor drops to about 4 kPa after about 30 minutes. The temperature of chlorination distillation is set to 110℃. 1000L of industrial hydrochloric acid is added to start heating and chlorination distillation. During the heating process, the high-concentration hydrochloric acid boils and distills out of the reactor. The acidity inside the reactor is about 7.5 mol / L.

[0050] Three hours after the start of chlorination distillation, some acid was collected in the storage bottle, with no crude germanium tetrachloride. Liquid germanium tetrachloride (1.5L) was collected in the tail gas collection bottle, containing 0.956 kg of germanium metal. 25 kg of sodium hydroxide was added to the 500L alkaline tail gas absorption tower, increasing the germanium content in the alkaline solution by 2.1 g / L. 1.050 kg of germanium was recovered, resulting in a direct recovery rate of 20.69% and a recovery rate of 43.42%. This indicates that when recovering germanium from the neutralization slag based on the solid-liquid ratio of the germanium concentrate, the reaction is violent, the distillation effect is poor, and the distilled germanium tetrachloride is significantly shifted downstream.

[0051] The germanium-containing waste acid produced by the secondary distillation of S5 is neutralized and then placed in the slag storage for transfer.

Claims

1. A process for the recovery of germanium from low acidity distillation residue containing germanium by leaching with a surfactant, characterized in that, The method comprises the following steps: S1: After one distillation, the waste acid is neutralized by lime, and the cake is filtered by a filter press for use; S2: The output neutralized residue filter cake is analyzed for germanium content, and the neutralized residue with germanium content higher than 0.4% is selected for use; S3: The prepared neutralized residue is fed into a chlorination distillation reaction kettle, 3-5 times of the amount of germanium metal in the neutralized residue is added to manganese dioxide, the tail gas system of the reaction kettle is closed, the solid feeding port is closed, industrial hydrochloric acid with a concentration of 10 mol / L is added according to the mass-volume ratio of the neutralized residue and hydrochloric acid being 1:1-3; S4: Low-temperature pre-reaction for 1.5-2.5 hours: the temperature of the distillation reaction kettle is controlled at 45-65°C, the pressure in the reaction kettle is controlled at 10-15 kPa, a surfactant with a mass-volume concentration of 100 g / L is added according to the mass-volume ratio of the neutralized residue and the surfactant being 10:1-10:3 to increase the pre-reaction effect, and the surfactant is sodium dodecyl benzene sulfonate; S5: Heating and distillation: the pre-reacted material is heated to 110°C, a small amount of hydrochloric acid is added for multiple times, and the acidity of the chlorination distillation in the reaction kettle is controlled at 4-5.5 mol / L; S6: The germanium-containing waste acid after the second distillation is neutralized by lime and then stored in a residue storage for transfer.