A method for leaching zinc and separating germanium from neutralized germanium slag containing zinc silicate by ferric roasting-ammonia leaching

Abstract

The invention discloses a method for leaching zinc and separating germanium from zinc-neutralized germanium-containing slag containing zinc silicate, belonging to the industry of comprehensive utilization of secondary metal resources. The method uses zinc-neutralized germanium-containing slag containing zinc silicate as raw material, controls the introduction of an appropriate amount of ferrous carbonate, and adjusts the molar ratio of ferrous carbonate to zinc silicate to 1.0 - 3.0:1; then roasts in an oxidizing atmosphere to obtain a roasted product with reconstituted ore phase; finally, ammonia leaching method can be used to selectively leach zinc. The method for recovering zinc by ore phase reconstruction - ammonia leaching is adopted in the invention. After the decomposition of ferrous carbonate, it reacts with zinc silicate in an oxidizing atmosphere, and zinc silicate is well converted into zinc oxide. The leaching rate of zinc can reach over 92% after two-stage ammonia leaching, and germanium is enriched in the ammonia leaching residue as raw material for germanium extraction. The oxide after the decomposition of ferrous carbonate enters the slag without introducing new impurities, and can increase the iron content in the slag, which is beneficial to the resource utilization of iron. The invention is simple and controllable, has a high leaching rate of zinc and a good separation effect of germanium, and is convenient for large-scale industrial application.

Description

Technical Field

[0001] The invention discloses a method for leaching zinc and separating germanium from zinc germanium silicate-containing neutralized germanium slag by ferric roasting-ammonia leaching method. In particular, after pretreatment of the neutralized germanium slag, zinc is selectively leached, and components such as germanium, iron, silicon, aluminum, calcium, and magnesium in the slag do not enter the solution but are further enriched in the slag, belonging to the technical field of comprehensive utilization of secondary resources. Background Art

[0002] A variety of rare metals are often associated with zinc sulfide ore. Due to isomorphous substitution and sulfur affinity, germanium easily enters the lattice of sphalerite and is enriched. High-germanium zinc sulfide ores in China are mainly distributed in Guangdong, Yunnan, Guizhou, Sichuan and other places. The two mainstream processes for hydrometallurgical zinc smelting are zinc sulfide ore roasting-leaching-electrowinning and direct oxygen pressure acid leaching-purification-electrowinning. During the zinc smelting process, germanium and zinc dissolve in sulfuric acid solution together.

[0003] The most commonly used methods for precipitating germanium from solution are tannin precipitation and zinc powder replacement, and both methods are widely used in production. The tannin germanium precipitation process is short and the process is simple. The produced tannin germanium concentrate can be used as a germanium concentrate for direct germanium extraction, but the single consumption of tannic acid is large, and a small amount of tannic acid dissolves into the zinc sulfate solution and affects the electrowinning of zinc. Zinc powder replacement for germanium removal will generate arsine gas. Zinc powder replacement will also replace metals with more positive electrode potentials such as copper, cadmium, and gallium at the same time. The consumption of zinc powder is large and the excessive zinc powder enters the replacement slag together with other impurities, resulting in a low grade of germanium-containing replacement slag and unable to directly chlorinate and distill. Germanium in the replacement slag needs to be recovered through a complex process of oxygen pressure acid leaching-iron removal-extraction-stripping-precipitation of germanium. Commonly used germanium extractants such as YW-100, LIX63, N235, etc. have strong water solubility, resulting in that the zinc-containing raffinate after germanium extraction cannot be directly electrowon but can only be used to prepare zinc salts, and the germanium precipitation mother liquor contains fluorine and is difficult to dispose.

[0004] In addition to the above two technologies for precipitating germanium from zinc sulfate solution, the technology for precipitating germanium using iron salts or magnesium salts as a medium and using zinc calcine, calcium oxide / hydroxide, sodium hydroxide, sodium carbonate, etc. as neutralizing agents has a long history, but it is mainly applied in the field of small-scale germanium recovery and the recovery of germanium associated with other non-ferrous metal ores. In recent years, due to the high price of tannic acid, and the technology of zinc powder replacement and subsequent germanium extraction has significant disadvantages such as low total recovery rate, high cost, and ineffective zinc recovery, some large-scale hydrometallurgical zinc smelting enterprises have improved the traditional neutralization germanium precipitation process, neutralized the sulfuric acid leaching solution of zinc oxide fume or the oxygen pressure acid leaching solution of zinc sulfide concentrate, and zinc, germanium and iron precipitate together. At the same time, some silicon, arsenic, aluminum, lead, and manganese in the solution also precipitate together. By optimizing the process, the germanium content in the neutralized germanium slag can be increased to 1.0% - 2.0%. The neutralized germanium slag contains a certain amount of zinc and can be used as a secondary resource for zinc recovery.

[0005] There are many disposal methods for non-sulfur secondary zinc resources such as neutralized germanium slag. The pyrometallurgical process can use the Wiltz rotary kiln, fuming furnace, Ausmelt furnace, kivcet furnace and other high-temperature reduction volatilized zinc, but germanium, lead, aluminum, arsenic and silicon also volatilize into the smoke at the same time, and acid leaching is still required later, and the enrichment multiples of pyrometallurgical volatilized zinc and germanium are low. The most commonly used leaching solvent for wet process is generally sulfuric acid, but the silicon part in the neutralized germanium slag exists in the form of zinc silicate. When the neutralized germanium slag is leached with sulfuric acid, whether it is atmospheric pressure leaching or high pressure leaching, there is a problem that zinc, germanium and iron are dissolved into the solution together and cannot be separated, and silicon will hydrolyze to form silica gel, which will adsorb part of the germanium, resulting in the insolubility of part of the germanium and difficulty in filtering the leachate, resulting in the loss of zinc and germanium. For the neutralized germanium slag with a germanium content greater than 1%, the neutralized germanium slag can be used as a germanium concentrate for hydrochloric acid distillation, and then re-distillation and rectification, as well as hydrolysis to prepare high-purity germanium dioxide, but zinc, iron and other components remain in the distillation waste acid. It is difficult to recover zinc in the chlorination system. Generally, lime precipitation is added, and zinc, iron and other heavy metals enter the slag again to become solid waste, and zinc cannot be effectively recovered. In addition, the content of heavy metals, arsenic, chloride ions, etc. in the distillation waste acid is high, which makes environmental protection treatment difficult and the disposal cost high. Using sodium hydroxide direct alkaline leaching, amphoteric metals such as zinc, germanium, arsenic, silicon, and aluminum in the neutralized slag will dissolve at the same time, but due to the complex physical phases of zinc and germanium and the high silicon content, 40% to 50% of zinc and germanium cannot be leached, and the zinc and germanium entering the alkali solution exist in the form of zincate and germanate anions, respectively, and the separation of the two is difficult. The zinc in the neutralized germanium slag mainly exists in the form of zinc silicate and zinc carbonate, while the iron mainly exists in the form of siderite (ferrous carbonate) and ferrous silicate. Zinc silicate is included and wrapped in the neutralized germanium slag and is difficult to be directly leached by ammonia solvents. Converting zinc silicate into zinc oxide through mineral phase reconstruction is the key to improving the zinc recovery rate.

[0006] Chinese patent CN109097557 B uses willemite resources as raw materials, adopts sodium roasting at 800-900℃, mineral phase reconstruction-water leaching method to extract zinc, zinc oxide is selectively dissolved, and then the zinc resources are efficiently recovered from the willemite resources. Chinese patent CN 108893597 B uses willemite resources as raw materials, adopts calcification roasting at 1240-1280℃, and uses NH4Cl-NH3·H2O solution as leaching agent for ammonia leaching to recover zinc. Chinese patent CN 105624411 A adds calcium oxide to gas ash, microwave roasts at 300-500℃, grinds the roasted sand, and then leaches ammonia in an ultrasonic field with an ultrasonic power of 600-1200W to achieve efficient leaching of zinc.

[0007] In the above-mentioned ore phase reconstruction method, in Chinese Patent CN109097557 B and Chinese Patent CN 108893597 B, the roasting temperature is high, resulting in high energy consumption and complex equipment, and introducing new impurity elements sodium or calcium. Chinese Patent CN 105624411 A uses microwave and ultrasonic devices to intensify the roasting and leaching processes, with high equipment requirements and complex operations, and introducing new impurity element calcium. To efficiently, low-costly, and environmentally friendly leach and neutralize zinc in germanium slag, the present invention proposes a new method with good zinc leaching rate, good germanium separation effect, high recovery rate, less auxiliary material consumption, short process, simple and easy-to-operate equipment, recyclable reagents, and no introduction of new impurities. Summary of the Invention

[0008] The present invention provides a method for leaching zinc and separating germanium from neutralized germanium slag containing zinc silicate by ferric roasting-ammonia leaching method. Adopting a combined pyrometallurgy-hydrometallurgy process, zinc silicate is ammoniacally leached after ore phase reconstruction, and germanium and iron are enriched and retained in the slag as secondary resources for germanium extraction and iron resource utilization, thereby realizing the comprehensive utilization of valuable resources in neutralized germanium slag in the zinc hydrometallurgy process and achieving the goals of high-value utilization of solid waste and no external discharge of waste water and waste residue.

[0009] The specific process steps to achieve the object of the present invention are as follows:

[0010] (1) The neutralized germanium slag containing zinc silicate is dried at low temperature and then crushed to obtain raw materials with a specific particle size;

[0011] (2) Ferrous carbonate is added to the raw materials obtained in step (1), and thoroughly mixed to obtain a mixed powder. The mixed powder is filled into a container and roasted in an oxidizing atmosphere, and the roasted product is obtained after cooling; in the mixed powder, the molar ratio of ferrous carbonate to zinc silicate in the neutralized germanium slag is 1.0 - 3.0:1;

[0012] (3) The roasted product obtained in step (2) is subjected to ammonia leaching treatment to dissolve and leach zinc oxide. After solid-liquid separation, a zinc-containing ammoniacal filtrate and a leaching residue are obtained

[0013] In the present invention, fine ferrous carbonate powder is added to the raw materials obtained in step (1), and thoroughly mixed to obtain a mixed powder. The mixed powder is filled into a container and roasted in an oxidizing atmosphere to decompose zinc carbonate into zinc oxide while zinc silicate is transformed into zinc oxide through ore phase reconstruction, and the roasted product is obtained after cooling;

[0014] In the present invention, the roasted product obtained in step (2) is put into a leaching tank, and through ammonia leaching treatment, zinc oxide is dissolved and leached. After solid-liquid separation, a zinc-containing ammoniacal filtrate and a leaching residue are obtained.

[0015] Preferably, the ferrous carbonate can be provided by high-grade siderite or by-product industrial-grade ferrous carbonate, as well as ferrous carbonate precipitated from ferrous ions in the zinc sulfate solution during the neutralization process; of course, other forms of ferrous sulfate can also be used in the present invention.

[0016] Preferably, the germanium-neutralized slag containing zinc silicate is from the hydrometallurgical zinc industry and is the precipitate obtained by adding a neutralizing agent to the germanium-containing zinc sulfate solution. Moreover, the present invention is applicable to other materials containing zinc silicate.

[0017] Preferably, the temperature for low-temperature drying is 60-120 °C to avoid the high-temperature decomposition of siderite, and the particle size after crushing is controlled to be less than 74 μm.

[0018] Preferably, in step (2), in the mixed powder obtained by adding fine ferrous carbonate powder, the molar ratio of ferrous carbonate to zinc silicate in the germanium-neutralized slag is 1.0-3.0:1.

[0019] Theoretically speaking, the molar ratio of ferrous carbonate powder to zinc silicate in the mixed powder of 3.0:1 is sufficient. At this time, adding more ferrous carbonate powder will waste auxiliary materials and reduce the germanium content in the ammonia leaching residue. Therefore, in the present invention, the molar ratio of ferrous carbonate to neutralized zinc silicate in the mixed powder is controlled to be 1.0-3.0:1.

[0020] Preferably, the zinc content in the germanium-neutralized slag containing zinc silicate is 8-22 wt%, the germanium content is 0.4-2.0 wt%, the iron content is 10-25 wt%, and the silicon dioxide content is 1.0-9.0 wt%.

[0021] Currently, in the germanium-neutralized slag containing zinc silicate, the main forms of iron include siderite and fayalite, and the main forms of zinc include zinc carbonate and zinc silicate. A small amount exists in the form of sulfides, oxides and other forms in the raw material slag.

[0022] Preferably, the molar ratio of the added amount of ferrous carbonate plus the siderite content in the neutralized slag to zinc silicate in the germanium-neutralized slag is 1.0-3.0:1. Preferably, it is 1.5-2.0:1. In the present invention, the amount of ferrous carbonate introduced additionally is controlled because the amount of ferrous carbonate originally in the raw materials may not be sufficient to completely ironize the zinc silicate in the materials; however, if too much ferrous carbonate is introduced additionally, it will cause waste and reduce the germanium content in the slag after zinc leaching, and if it is too low, the zinc silicate cannot be completely ironized, reducing the zinc leaching rate.

[0023] Preferably, the oxidative roasting is carried out in a rotary kiln, crucible furnace, tube furnace or oven, and the materials and oxygen are in full contact during the reaction process.

[0024] Preferably, the roasting temperature is controlled at 350-600 °C, preferably 450-500 °C, and more preferably 470-490 °C, and the roasting time is 100-300 min, preferably 120-240 min.

[0025] Preferably, the roasted product is cooled naturally or quenched rapidly with water. Of course, other cooling methods can also be used in the present invention.

[0026] Preferably, in the step (3), a stirring leaching method is adopted, and the leaching device is airtight and resistant to ammonia corrosion.

[0027] Preferably, in the step (3), ammonium carbonate-ammonia water or ammonium sulfate-ammonia water can be used as the leaching agent, and the molar concentration ratio of NH4 + ions to free ammonia NH3 in the leaching agent is (0.25-4.0):1, and the total ammonia concentration is 4-9 mol / L.

[0028] Preferably, in the step (3), the ammonia leaching is carried out at a liquid-solid ratio of (5-20):1, a reaction temperature of 40-65 °C, and a stirring speed of 400-800 r / min for heat preservation reaction for 60-240 min, preferably 120-180 min.

[0029] In the present invention, the zinc-containing ammonia filtrate can be recycled for zinc recovery by existing methods.

[0030] Through liquid-solid separation, the leaching solution can be formulated and then subjected to ammonia leaching again. The contents of germanium and iron in the leaching residue increase and can be used as raw materials for germanium extraction and iron resource utilization.

[0031] The present invention selectively leaches zinc with a mixed ammonia leaching agent. The ammonia leaching solution is purified and then zinc is recovered. The leaching residue can be used as a raw material for germanium extraction and iron resource utilization after filtration and washing.

[0032] The present invention uses neutralized germanium slag as the raw material and adopts the method of ore phase reconstruction-ammonia leaching to dissolve zinc. Compared with zinc silicate and zinc ferrite, zinc oxide is easily soluble in ammonia solution. Based on this principle, the present invention proposes a technical scheme of leaching zinc by the method of ironization roasting pretreatment followed by ammonia leaching. This scheme utilizes the original ferrous carbonate in the raw material, and the insufficient part can be added additionally. Roasting is carried out in an oxidizing atmosphere to convert the structurally stable zinc silicate ore into zinc oxide with a simple structure. The oxides decomposed from the excessive ferrous carbonate will not be leached by ammonia, and are used together with the original iron in the raw material for iron resource utilization. The zinc oxide in the roasted product will be selectively dissolved, so as to realize the efficient recovery of zinc resources from the neutralized germanium slag. The main chemical reactions involved in the present invention are as follows

[0033] FeCO3→FeO+CO2↑

[0034] ZnCO3→ZnO+CO2↑

[0035]

[0036]

[0037]

[0038]

[0039]

[0040]

[0041] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0042] (1) Ferrous carbonate is selected as the ironizing agent for ore phase reconstruction. Ferrous carbonate is inexpensive and easily available, and does not introduce new impurity elements. Moreover, the existing ferrous carbonate in the raw materials can be utilized to reduce the consumption of auxiliary materials. The temperature at which ferrous carbonate decomposes and reacts with zinc silicate is low, and the roasting process is easy to implement and energy-saving. At the same time, the oxides decomposed from the introduced ferrous carbonate enter the slag without introducing new impurities, which can increase the iron content in the slag and is beneficial to the resource utilization of iron. Compared with the ore phase reconstruction methods of sodiumization and calcification, the present invention does not require the addition of calcifying agents and sodiumizing agents, and has a low roasting temperature and low energy consumption.

[0043] (2) High-efficient leaching and recovery of zinc. In the present invention, zinc silicate is transformed into zinc oxide that is easy to leach through the ore phase reconstruction method of ironizing roasting. After mixing with an ammoniacal leaching agent and secondary ammonia leaching, the zinc leaching rate can be greater than 92%.

[0044] (3) Enrichment of germanium and iron and separation from zinc. The added ironizing agent, the iron originally in the raw materials, and germanium are almost insoluble in the ammoniacal leaching agent, and the leaching rates of both are lower than 0.01%. Due to the dissolution of zinc, the reduction of the slag directly leads to an increase in the iron and germanium content therein, making it easier to extract germanium and resource utilization of iron.

[0045] (4) The leaching agent can be recycled. The ammoniacal leaching solution can be used as a leaching agent for recycling after being formulated. There are few impurity elements in the ammoniacal leaching solution. After impurity removal with zinc powder, it can be subjected to sulfide precipitation or direct electrowinning. Compared with acid leaching and sodium hydroxide leaching, the present invention has low acid-base consumption, strong selectivity for zinc, does not produce silica gel during the reaction, is easy to filter, and the leaching solution can recover ammonia.

[0046] The present invention adopts a combined pyrometallurgical - hydrometallurgical process, with low roasting and ammonia leaching temperatures and low energy consumption; the leaching agent can be recycled, and compared with other methods, it does not consume a large amount of acids and alkalis; no silica gel is generated during the leaching process, and it is easy to filter after ammonia leaching; the ferritizing agent has good roasting mineral phase reconstruction effect, iron enters the slag, and no new impurities are introduced; the ammonia leaching method has good zinc recovery effect, low leaching cost, high selectivity for zinc, and impurities such as germanium, iron, calcium, magnesium, silicon, and aluminum are not leached, and the ammonia leaching residue can be used as a raw material for germanium extraction and iron resource utilization; there is no wastewater and waste residue discharge throughout the process, which is green and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Appendix Figure 1 is the process flow chart designed for the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0048] The following further describes the present invention with reference to specific examples, so that those skilled in the art can better understand the present invention and implement it, but the examples are not intended to limit the present invention.

[0049] Example 1

[0050] The raw materials selected in the following examples are from the zinc smelting process of roasting - leaching - electrowinning. After the leaching residue is subjected to high - temperature carbon reduction in a fuming furnace, zinc, germanium and other components volatilize into the dust. After the dust is subjected to two - stage counter - current sulfuric acid leaching, zinc, germanium and part of the iron enter the solution. Zinc roasting or zinc oxide is added to adjust the solution pH value to 5.0, and zinc, germanium and iron form precipitates and enter the slag. The main chemical components of this type of neutralized germanium slag are as follows:

[0051] Table 1 Main chemical components of the neutralized germanium slag in the sulfuric acid leaching solution of fuming furnace dust (wt%)

[0052]

[0053] This type of neutralized germanium slag contains ferrous carbonate and zinc silicate.

[0054] The neutralized germanium slag is loaded into a boat, dried in a drying oven at 85°C to remove moisture and then crushed to - 200 mesh. A certain amount of ferrous carbonate powder is weighed (the amount of introduced ferrous carbonate powder is added according to 3wt% of the material. After the additional introduction of ferrous carbonate powder, the molar ratio of ferrous carbonate powder to zinc silicate in the neutralized germanium slag is 1.8:1). After uniform mixing, it is transferred into a tubular furnace, heated uniformly to the roasting temperature of 480°C, kept warm for 3h and then discharged. After ferritization treatment, the zinc phase in the neutralized slag changes, and the weight loss rate is 18.62%.

[0055] Weigh a certain amount of the roasted product, and select ammonia - ammonium carbonate (total ammonia 7M, [NH4 +:(The molar ratio of [NH3] is 2.5:1) is an ammonia-based solvent. According to the liquid-solid ratio of 20:1, the ammonia-based leaching agent is pumped into a plastic-lined steel reaction tank. After starting the stirring, the neutralized germanium slag is put into the plastic-lined steel reaction tank. Heat is raised to 50 °C, and after maintaining the temperature and continuing the reaction for 4 hours, heating is stopped. After the temperature drops to room temperature, the pulp in the reaction tank is pumped to an underflow washable filter press. The discharged filter cake starts the secondary ammonia leaching. The filtrate from the secondary ammonia leaching is returned to the first ammonia leaching process. The filter cake after filtration is washed twice with medium water, and the filtrate can be stored separately or incorporated into the ammonia leaching solution. The ammonia leaching solution is adjusted and recycled for leaching 6 to 9 times to make the zinc concentration in the ammonia leaching solution reach more than 20 g / L, and the ammonia leaching solution is sent to the zinc extraction process. In this example, in the first ammonia leaching, the leaching rate of zinc can reach 85.98%;

[0056] Germanium and iron in the neutralized slag are hardly soluble in the ammonia-based leaching agent, and the dissolution rates of germanium and iron are both lower than 0.01%. After ammonia leaching, the zinc content in the neutralized iron slag is reduced to 1.71%, the germanium content is increased to 2.15%, and the iron content is increased to 22.53%.

[0057] Example 2:

[0058] The raw materials selected in the following example are the neutralized precipitate slag obtained by adding zinc roasting or zinc oxide fume to the post-oxygen pressure acid leaching solution in the zinc hydrometallurgy process. Most of the germanium and part of zinc, iron, aluminum, silicon, and arsenic enter the slag together. The main chemical components of this type of neutralized germanium slag are shown in Table 2.

[0059] Table 2 Main chemical components of the neutralized germanium slag of the oxygen pressure acid leaching solution (wt%)

[0060]

[0061] The neutralized germanium slag is loaded into a boat and dried in a drying oven at 105 °C to remove moisture and then crushed to -200 mesh. A certain amount of ferrous carbonate powder is weighed (the amount of ferrous carbonate powder introduced is 5 wt% of the feeding amount. After the additional introduction of ferrous carbonate powder, the molar ratio of ferrous carbonate powder to zinc silicate in the neutralized germanium slag is 2:1). After being evenly mixed, it is transferred into a tubular furnace and heated evenly to the roasting temperature of 490 °C. After holding for 4 h, the material is discharged. After the ironization treatment, the zinc phase in the neutralized slag changes, and the weight loss rate is 9.16%.

[0062] Weigh a certain amount of the cooled roasting product into a plastic-lined steel reaction tank, and select ammonia water-ammonium sulfate (total ammonia 5M, [NH4 +:The ammonia-based solvent with a molar ratio of [NH3] of 1:2 is added according to a liquid-solid ratio of 15:1. After starting stirring, the temperature is raised to 60 °C, and after holding the temperature and continuing the reaction for 3 hours, the heating is stopped. After cooling to room temperature, the supernatant is sent to the purification process, and zinc is recovered after purification. The underflow is pumped to the second plastic-lined steel reaction tank, and an ammonia water-ammonium sulfate leaching agent is added according to a liquid-solid ratio of 15:1. After secondary ammonia leaching, the leaching solution is pressure-filtered, and the filtrate is returned to the first-stage ammonia leaching after adjusting the concentrations of [NH4 + and [NH3]. The filter residue can be used as a raw material for germanium and iron resource recovery after washing and drying. In this example, after the first-stage ammonia leaching, the leaching rate of zinc can reach 86.75%;

[0063] After ammonia leaching, the zinc content in the neutralized iron slag is reduced to 2.34%, the germanium content is increased to 0.65%, and the iron content is increased to 31.78%.

[0064] Comparative Example 1

[0065] Other conditions are the same as those in Example 1, except that: no ferrous carbonate powder is additionally introduced; after the first-stage ammonia leaching, the leaching rate of zinc is 85%.

[0066] Comparative Example 2

[0067] Other conditions are the same as those in Example 1, except that: without ironizing roasting, directly after the first-stage ammonia leaching, the leaching rate of zinc is 69.51%.

Claims

1. A method for leaching zinc and separating germanium from neutralized germanium slag containing zinc silicate by ferric roasting - ammonia leaching method, characterized in that, It includes the following steps: (1) Low-temperature drying and then crushing the neutralized germanium slag containing zinc silicate to obtain raw materials with a predetermined particle size; (2) Adding ferrous carbonate to the raw materials obtained in step (1), fully mixing to obtain a mixed powder. The mixed powder is put into a container and roasted in an oxygen atmosphere, and the roasted product is obtained after cooling. In the mixed powder, the molar ratio of ferrous carbonate to zinc silicate in the neutralized germanium slag is 1.0 - 3.0:1; (3) Performing ammonia leaching treatment on the roasted product obtained in step (2) to dissolve and leach zinc oxide. After solid-liquid separation, a zinc-containing ammonia leaching filtrate and leaching residue are obtained.

2. The method for leaching zinc and separating germanium from neutralized germanium slag containing zinc silicate by ferric roasting - ammonia leaching method according to claim 1, characterized in that: The neutralized germanium slag containing zinc silicate comes from the hydrometallurgical zinc industry.

3. The method for leaching zinc and separating germanium from neutralized germanium slag containing zinc silicate by ferric roasting - ammonia leaching method according to claim 1, characterized in that: The drying temperature is 60 - 120 °C, and the particle size of the neutralized germanium slag obtained by crushing is less than 74 μm.

4. The method for leaching zinc and separating germanium from neutralized germanium slag containing zinc silicate by ferric roasting - ammonia leaching method according to claim 1, characterized in that: In step (2), in the mixed powder obtained by adding ferrous carbonate, the molar ratio of ferrous carbonate to zinc silicate in the neutralized germanium slag is 1.5 - 2.0:

1.

5. The method for leaching zinc and separating germanium from neutralized germanium slag containing zinc silicate by ferric roasting - ammonia leaching method according to claim 1, characterized in that: The zinc content in the neutralized germanium slag containing zinc silicate is 8 - 22 wt%, the germanium content is 0.4 - 2.0 wt%, the iron content is 10 - 25 wt%, and the silicon dioxide content is 1.0 - 9.0 wt%.

6. The method for leaching zinc and separating germanium from neutralized germanium slag containing zinc silicate by ferric roasting - ammonia leaching method according to claim 1, characterized in that: The roasting is carried out in a rotary kiln, crucible furnace, or tubular furnace, and the materials and oxygen are in full contact during the reaction process.

7. The method for leaching zinc and separating germanium from neutralized germanium slag containing zinc silicate by ferric roasting - ammonia leaching method according to claim 1, characterized in that: Control the roasting temperature to be 350 - 600 °C and the roasting time to be 100 - 300 min.

8. The method for leaching zinc and separating germanium from neutralized germanium slag containing zinc silicate by ferric roasting - ammonia leaching method according to claim 1, characterized in that: In step (3), a stirring leaching method is adopted, and the leaching device is airtight and resistant to ammonia corrosion; In the step (3), ammonium carbonate - ammonia water or ammonium sulfate - ammonia water is used as the leaching agent, and the molar concentration ratio of NH4 + ions to free ammonia NH3 in the leaching agent is (0.25 - 4.0):1, and the total ammonia concentration is 4 - 9 mol / L; In step (3), the ammonia leaching is carried out at a liquid-solid ratio of (5 - 20):1, a reaction temperature of 40 - 65 °C, and a holding reaction for 60 - 240 min; during the holding reaction, control the rotation speed to be 400 - 800 revolutions per minute.

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