Method for leaching molybdenum from molybdenum calcine

Abstract

The invention belongs to the technical field of hydrometallurgy, and discloses a method for leaching molybdenum from molybdenum calcine, which comprises the following steps: mixing the molybdenum calcine and a solid ammonium source, and heating to obtain a transformed material; then, the transformed material is soaked in water and filtered, and a molybdenum-containing solution A is obtained; the ammonium molybdate is prepared through the technology combining heating transformation with water leaching, active molybdenum oxide in the molybdenum calcine is transformed into ammonium heptamolybdate / ammonium dimolybdate in the transformation process, the situation that local ammonia is excessive in the direct leaching process can be avoided, the leaching rate of MoO3 can be greatly increased, and the method is suitable for industrial production. During leaching, molybdenum enters a solution in a relatively pure ammonium heptamolybdate / ammonium dimolybdate form, so that the introduction of impurities is reduced, the burden of subsequent purification and impurity removal steps is reduced, and the impurity removal cost is reduced; the method is simple in process, does not need to use a large amount of strong acid or strong alkali or other strong-corrosivity reagents, reduces the dosage of the reagents in the leaching and subsequent processes, is wide in raw material source and low in price, is low in production cost, and is beneficial to industrialization and marketization.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrometallurgy, and relates to a method for preparing molybdenum-containing products, specifically to a method for leaching molybdenum from molybdenum roast. Background Art

[0002] Molybdenum roast, also known as industrial molybdenum oxide, is an important chemical raw material, which is obtained by roasting and smelting molybdenum concentrate. Molybdenum roast is used to prepare ammonium polymolybdate, which is an important chemical product mainly used in the fields of powder metallurgy and electronics industry, and is the basic raw material for manufacturing molybdenum powder.

[0003] Patent CN112758983A discloses a method for preparing ammonium heptamolybdate. (1) Mix molybdenum roast with a leaching agent, adjust the pH value and reaction temperature to obtain a sodium molybdate solution; (2) Add a quaternary ammonium salt to the ammonium molybdate solution in step (1), extract molybdenum under alkaline conditions, and then add ammonium bicarbonate to the extract to obtain an ammonium molybdate solution; (3) The ammonium molybdate solution is subjected to intermittent vacuum evaporation crystallization under negative pressure to obtain wet ammonium heptamolybdate, and then dried to obtain ammonium heptamolybdate.

[0004] Patent CN107986332A discloses a method for reducing potassium in ammonium molybdate solution. The method includes the following steps: Step 1, wash molybdenum roast, and filter to obtain a filter cake; Step 2, put the filter cake obtained in step 1 into ammonia water with a pH of 8.0 - 9.0 for ammonia leaching, and filter to obtain a filtrate; Step 3, age the filtrate obtained in step 2, and filter to obtain an ammonium molybdate solution; during the aging process, control the pH of the filtrate to be 8.5 - 9.0, the molybdenum content in the ammonium molybdate solution is 250 g / L - 285 g / L, and the potassium content is less than 30 mg / L.

[0005] In the above patents, ammonia water or sodium hydroxide is used for leaching to obtain an alkaline ammonium molybdate solution or a sodium molybdate solution. Among them, the sodium molybdate solution needs to be transformed into an ammonium molybdate solution through ion exchange or solvent extraction; the purified alkaline ammonium molybdate solution is prepared into weakly acidic and low ammonium-molybdenum ratio ammonium tetramolybdate (NH4)2Mo4O 13 , ammonium dimolybdate (NH4)2Mo2O7, ammonium heptamolybdate (NH4)6Mo7O 24 . This method is difficult to avoid problems such as large consumption of acid-base auxiliary materials, heavy burden on ammonia-nitrogen wastewater treatment, and high production costs. Summary of the Invention

[0006] Aiming at the defects and deficiencies existing in the prior art, the present invention provides a method for leaching molybdenum from molybdenum roast.

[0007] A method for leaching molybdenum from molybdenum roast according to the present invention includes the following steps: Step 1: Mix molybdenum roasting ore and solid ammonium source and then heat to obtain a transformed material. Step 2: Leach the transformed material with water and filter to obtain molybdenum-containing solution A.

[0008] After research, the inventors found that in the prior art, usually an alkaline (NH4)2MoO4 solution is obtained by leaching, and the solution contains a large amount of free ammonia, and the ammonium-molybdenum ratio is much greater than 2. Thus, when preparing ammonium polymolybdate products with weak acidity and low ammonium-molybdenum ratio (ammonium dimolybdate (NH4)2Mo2O7, ammonium heptamolybdate (NH4)6Mo7O 24 ammonium tetramolybdate (NH4)2Mo4O 13 ), the leaching solution contains excessive ammonium ions and free ammonia. There is a problem that ammonia is volatile during the leaching process, resulting in a poor operating environment, increasing the burden of subsequent ammonium / ammonia recovery and treatment, and at the same time generating a large amount of high-salt wastewater.

[0009] First, molybdenum roasting ore reacts with ammonium source under heating conditions. Molybdenum trioxide in molybdenum roasting ore reacts with ammonium source to form ammonium heptamolybdate or ammonium dimolybdate, etc. Ammonium heptamolybdate / dimolybdate has good solubility in water. Compared with directly leaching molybdenum roasting ore with water, ammonium-containing solution or ammonia water, heating transformation first and then water leaching can greatly improve the leaching rate of MoO3. Second, during the heating transformation process, the properties of some impurities in molybdenum roasting ore will change, showing different solubilities from molybdenum compounds during subsequent water leaching. Some metal oxide impurities may not react with ammonium source or the generated compounds are insoluble in water, while ammonium heptamolybdate / dimolybdate can dissolve in water. In this way, during water leaching, preliminary separation of molybdenum from some impurities can be achieved, and molybdenum can enter the solution in the form of relatively pure ammonium molybdate, reducing the introduction of impurities, lightening the burden of subsequent purification and impurity removal steps, and reducing the impurity removal cost. Third, the method of transformation first and then water leaching is relatively simpler than some complex leaching processes, such as acid leaching or alkali leaching, etc. It does not require the use of a large amount of strong acids or strong alkalis and other corrosive reagents, reducing the dosage of reagents during leaching and subsequent processes, reducing the reagent cost, and reducing the corrosion of equipment, reducing the operation risk and environmental pollution risk. Moreover, the ammonium source is widely available and the dosage is small, further reducing the production cost.

[0010] Preferably, in Step 1, the solid ammonium source is any one or two of ammonium carbonate and ammonium bicarbonate. [[ID=]17]

[0011] After research, the inventors found that during the transformation process, appropriate heating is beneficial to promote the transformation. The lower the heating temperature, the longer the required heating time, and the higher the heating temperature, the shorter the required heating time.

[0012] Preferably, the main component of the molybdenum-containing solution A obtained in Step 2 is ammonium heptamolybdate or ammonium dimolybdate.

[0013] Preferably, in step 1, when the molar ratio of MoO3 in molybdenum roast to NH4 in the ammonium source is 1:0.7 - 0.9, the main component in molybdenum-containing solution A is ammonium heptamolybdate. +

[0014] Preferably, in step 1, the heating temperature is 30 - 70°C and the heating time is 0.5 - 5 h.

[0015] Preferably, in step 1, when the molar ratio of MoO3 in molybdenum roast to NH4 in the ammonium source is 1:0.95 - 1.25, the main component in molybdenum-containing solution A is ammonium dimolybdate. +

[0016] The inventors found through research that a higher ammonium ion concentration helps to promote the reaction towards the formation of ammonium dimolybdate, enabling MoO3 in molybdenum roast to be more fully converted into ammonium dimolybdate, thereby increasing the conversion rate of molybdenum. An appropriately excessive amount of ammonium ions can ensure sufficient ionic concentration in the reaction system, promoting the formation of ammonium dimolybdate crystals. Moreover, the formation of ammonium dimolybdate requires a certain amount of ammonium ions to stabilize its structure. The ammonium dimolybdate solution formed within the above preferred range has good stability and is not prone to decomposition or conversion into other molybdates during subsequent processing. An appropriate excess of ammonium ions can maintain the pH of the solution within a certain range, preventing the decomposition or hydrolysis of ammonium dimolybdate due to changes in the solution pH, which is beneficial for subsequent purification, impurity removal, and crystallization operations, improving the product yield and quality.

[0017] Further preferably, in step 1, the heating temperature is 50 - 100°C and the heating time is 0.5 - 5 h.

[0018] Preferably, in step 2, when leaching the transformed material with water, the solid-liquid ratio is 1:1 - 10 g / mL.

[0019] The inventors found through research that a solid-liquid ratio of 1:1 - 10 g / mL when leaching the transformed material with water is beneficial for the preliminary separation of molybdenum and impurities. Some insoluble impurities are more likely to precipitate or be filtered out at this solid-liquid ratio, while ammonium molybdate salts can dissolve well in water, thus achieving an effective separation of molybdenum from some impurities and reducing the burden of subsequent impurity removal processes.

[0020] Preferably, the water leaching temperature is 30 - 100°C and the leaching time is 0.2 - 3 h.

[0021] The inventors found through research that water leaching at 30 - 100°C helps to break the binding force between some possible impurities and molybdates, making MoO3 more soluble, while impurities tend to remain in the solid phase, thereby increasing the leaching rate of molybdenum and the product purity.

[0022] Preferably, after step 2, a crystallization process is further included.

[0023] The inventor found through research that when the concentration of ammonium ions is relatively low, it is more inclined to form polyacid anions with a specific structure of ammonium heptamolybdate, which is conducive to the formation and growth of ammonium heptamolybdate crystals, reduces the generation of impurities such as other heteropolyacids or ammonium hydrogen molybdate, and thus improves the purity of the product.

[0024] Preferably, after evaporative crystallization of the ammonium heptamolybdate solution and filtration, the solid particles obtained are ammonium heptamolybdate.

[0025] More preferably, the evaporative crystallization temperature is 50 - 75°C (using negative pressure evaporation). After evaporative crystallization for a certain time, the temperature is lowered to 30°C and then filtered, and the solid particles obtained are ammonium heptamolybdate.

[0026] Preferably, an ammonium source is added to the ammonium heptamolybdate solution to adjust the pH value of the reaction system to 5.9 - 6.6, and then evaporative crystallization and filtration are carried out, and the solid particles obtained are ammonium dimolybdate.

[0027] More preferably, the crystallization temperature is 85 - 100°C. After evaporative crystallization for a certain time, the temperature is lowered to 30°C and then filtered.

[0028] More preferably, the ammonium source is any one or more than two of ammonium carbonate, ammonium bicarbonate, ammonium orthomolybdate, and ammonia water.

[0029] Preferably, an acid solution is added to the ammonium heptamolybdate solution to adjust the pH value of the reaction system to 2 - 4, and after standing and filtration, the solid particles obtained are ammonium tetramolybdate.

[0030] Preferably, the ammonium dimolybdate solution is subjected to evaporative crystallization, and the solid particles obtained are ammonium dimolybdate.

[0031] More preferably, the evaporative crystallization temperature is 85 - 100°C. After evaporative crystallization for a certain time, the temperature is lowered to 30°C and then filtered, and the solid particles obtained are ammonium dimolybdate.

[0032] Preferably, an acid solution is added to the ammonium dimolybdate solution to adjust the pH value of the reaction system to 5.0 - 5.7, and then evaporative crystallization and filtration are carried out, and the solid particles obtained are ammonium heptamolybdate.

[0033] More preferably, the evaporative crystallization temperature is 50 - 75°C. After evaporative crystallization for a certain time, the temperature is lowered to 30°C and then filtered, and the solid particles obtained are ammonium heptamolybdate.

[0034] In practical applications, negative pressure evaporation is used for crystallization. Negative pressure evaporation can achieve the same mass of evaporation in a shorter time, thereby improving production efficiency, and can achieve continuous and stable production, which is suitable for large-scale industrial production.

[0035] Preferably, an acid solution is added to the filtered ammonium dimolybdate solution to adjust the pH value of the reaction system to 2-4, and the mixture is allowed to stand and then filtered to obtain ammonium tetramolybdate as the solid particles.

[0036] More preferably, the acid solution is any one or more than two of nitric acid, hydrochloric acid, and sulfuric acid.

[0037] Preferably, after obtaining the molybdenum-containing solution A and before crystallization, an impurity removal process is further included. During impurity removal: an impurity remover is added to the molybdenum-containing solution A; the impurity remover is any one or more than two of ammonium sulfide and hydrogen sulfide.

[0038] The inventors found through research that ammonium sulfide and hydrogen sulfide can form insoluble sulfide precipitates with various metal impurity ions (such as Cu, Fe, As, etc.) in the solution, while molybdenum ions are relatively stable under this condition and do not form sulfide precipitates. Through this selective precipitation effect, impurities can be effectively separated from the solution, improving the purity of molybdenum. During the impurity removal process, the sulfide precipitates formed by the reaction of ammonium sulfide and hydrogen sulfide with impurity ions can be separated by methods such as filtration for further treatment or recycling, with less pollution to the environment. Moreover, these two impurity removers are relatively easy to decompose or treat under appropriate conditions and do not cause long-term harm to the environment.

[0039] Preferably, the impurity removal process is an ion exchange method or a solvent extraction method.

[0040] Preferably, step 1 is carried out under airtight conditions.

[0041] The inventors found through research that considering ammonia volatilization, carrying out the process under airtight conditions can reduce ammonia volatilization and improve the transformation effect.

[0042] Compared with the prior art, the present invention has the following obvious beneficial effects: By preparing ammonium molybdate through the heating transformation combined with water leaching process provided by the present invention, the active molybdenum oxide in molybdenum roasting ore is first transformed into ammonium heptamolybdate / ammonium dimolybdate during the transformation process, which can avoid the situation of local excessive ammonia during the direct leaching process, greatly improve the leaching rate of MoO3, and at the same time, molybdenum enters the solution in the form of relatively pure ammonium hepta / dimolybdate, reducing the introduction of impurities, lightening the burden of subsequent purification and impurity removal steps, and reducing the impurity removal cost; the process is simpler, does not require the use of a large amount of strong acids or strong alkalis and other corrosive reagents, reduces the reagent dosage in the leaching and subsequent processes, the raw materials are widely sourced and inexpensive, the production cost is low, which is conducive to industrialization and marketization. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is the XRD pattern of the molybdenum roasting ore raw material used in the specific embodiments and comparative examples of the present invention; Figure 2XRD pattern of the transformed material obtained in Step 1 of Example 1; Figure 3 XRD pattern of the leaching residue obtained in Step 2 of Example 1; Figure 4 XRD pattern of the solid particles obtained in Step 3 of Example 1; Figure 5 SEM image of the solid particles obtained in Step 3 of Example 1; Figure 6 XRD pattern of the solid particles prepared in Step 3 of Example 4; Figure 7 SEM image of the solid particles prepared in Step 3 of Example 4; Figure 8 XRD pattern of the solid particles prepared in Step 3 of Example 7; Figure 9 SEM image of the solid particles prepared in Step 3 of Example 7; Figure 10 XRD pattern of the transformed material prepared in Step 1 of Example 10; Figure 11 XRD pattern of the leaching residue obtained in Step 2 of Example 10. Detailed implementation manners

[0044] The present invention provides the following specific technical solutions.

[0045] To make the technical problems, technical solutions and technical advantages to be solved by the present invention clearer, the following will be described in detail with specific examples, but the protection scope of the present invention is not limited to the following specific embodiments.

[0046] Unless otherwise defined, all professional terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention.

[0047] Unless otherwise specifically stated, various raw materials, reagents, instruments and equipment used in the present invention can be obtained through market purchases or can be prepared by existing methods.

[0048] The content of MoO3 in the molybdenum roaster used in each embodiment and comparative example of the present invention is 72.54 wt.%, Figure 1 XRD pattern of the molybdenum roaster raw material used in the specific embodiments and comparative examples of the present invention, Figure 1 It can be seen that the molybdenum roaster mainly contains three substances: MoO3, CaMoO4, and Fe2(MoO4)3.

[0049] Example 1: A method for leaching molybdenum from molybdenum roasting ore, comprising the following steps: Step 1, mix 50 g of molybdenum roasting ore and 17 g of ammonium bicarbonate to obtain a mixed material, place the mixed material in a sealed container and heat it at 50 °C for 3 h to obtain a transformed material; Step 2, place 50 g of the transformed material in 0.1 L of water, leach it at 70 °C for 1 h, filter, add 1 g of ammonium sulfide (containing S 2- 8%) and let it stand for impurity removal, then filter to obtain a molybdenum-containing solution A and leaching residues.

[0050] Step 3, heat the molybdenum-containing solution A obtained in Step 2 to 70 °C for evaporation crystallization for 5 h, filter, and the obtained solid particles are ammonium heptamolybdate.

[0051] Figure 2 XRD pattern of the transformed material obtained in Step 1 of Example 1, from Figure 1 it can be seen that MoO3 in the molybdenum roasting ore has been transformed into (NH4)6Mo7O 24 .

[0052] Figure 3 XRD pattern of the leaching residues obtained in Step 2 of Example 1, from Figure 3 it can be seen that there is no (NH4)6Mo7O in the leaching residues 24 , thus it can be proved that (NH4)6Mo7O in the transformed material obtained in Step 1 24 is almost completely leached, which proves from the side that the leaching rate of molybdenum by the method provided by the present invention is high.

[0053] Figure 4 XRD pattern of the solid particles obtained in Step 3 of Example 1, from Figure 4 it can be seen that the solid particles prepared in Example 1 are mainly ammonium heptamolybdate.

[0054] Figure 5 SEM image of the solid particles obtained in Step 3 of Example 1.

[0055] Example 2: A method for leaching molybdenum from molybdenum roasting ore, comprising the following steps: Step 1, mix 50 g of molybdenum roasting ore and 16 g of ammonium bicarbonate to obtain a mixed material, place the mixed material in a sealed container and heat it at 40 °C for 2 h to obtain a transformed material; Step 2, place 50 g of the transformed material in 0.1 L of water, leach it at 40 °C for 0.5 h, filter, add 1 g of ammonium sulfide (containing S 2- 8%) and let it stand for impurity removal, then filter to obtain a molybdenum-containing solution A and leaching residues.

[0056] Step 3, heat the molybdenum-containing solution A obtained in Step 2 to 60 °C for evaporation crystallization for 7 h, filter, and the obtained solid particles are ammonium heptamolybdate.

[0057] Example 3: A method for leaching molybdenum from molybdenum roaster, comprising the following steps: Step 1: Mix 50 g of molybdenum roaster and 16.5 g of ammonium bicarbonate to obtain a mixed material. Place the mixed material in a sealed container and heat it at 60 °C for 4 h to obtain a transformed material. Step 2: Place 50 g of the transformed material in 0.2 L of water, leach it at 50 °C for 2 h, filter, add 1.5 g of ammonium sulfide (containing S 2- 8%) and let it stand for impurity removal, then filter to obtain a molybdenum-containing solution A and leaching residue.

[0058] Step 3: Heat the molybdenum-containing solution A obtained in Step 2 to 50 °C and evaporate it to crystallize for 10 h, then filter. The solid particles obtained are ammonium heptamolybdate.

[0059] Example 4: A method for leaching molybdenum from molybdenum roaster, comprising the following steps: Step 1: Mix 50 g of molybdenum roaster and 19.5 g of ammonium bicarbonate to obtain a mixed material. Place the mixed material in a sealed container and heat it at 30 °C for 0.5 h to obtain a transformed material. Step 2: Place 50 g of the transformed material in 0.15 L of water, leach it at 30 °C for 0.2 h, filter, add 1.5 g of ammonium sulfide (containing S 2- 8%) and let it stand for impurity removal, then filter to obtain a molybdenum-containing solution A and leaching residue.

[0060] Step 3: Add 4.5 g of solid ammonium bicarbonate powder to the molybdenum-containing solution A to adjust the pH value to 6.5, then heat it to 80 °C and evaporate it to crystallize for 3 h, then filter. The solid particles obtained are ammonium dimolybdate.

[0061] Figure 6 XRD pattern of the solid particles prepared in Step 3 of Example 4, from Figure 6 It can be seen that the solid particles prepared in Example 4 are mainly ammonium dimolybdate.

[0062] Figure 7 SEM image of the solid particles prepared in Step 3 of Example 4, from Figure 7 It can be seen that the solid particles prepared in Example 4 have no agglomeration phenomenon and the particles are uniform.

[0063] Example 5: A method for leaching molybdenum from molybdenum roaster, comprising the following steps: Step 1: Mix 50 g of molybdenum roaster and 15.5 g of ammonium bicarbonate to obtain a mixed material. Place the mixed material in a sealed container and heat it at 45 °C for 1.5 h to obtain a transformed material. Step 2: Place 50 g of the transformed material in 0.15 L of water, leach at 50 °C for 0.8 h, filter, add 1.5 g of ammonium sulfide (containing S 2- 8%) and let it stand for impurity removal, then filter to obtain molybdenum-containing solution A and leaching residue.

[0064] Step 3: Add 0.02 L of ammonium bicarbonate solution with a concentration of 2.10 mol / L to the molybdenum-containing solution A to adjust the pH value to 5.9, then heat to 90 °C and evaporate to crystallize for 3 h, filter, and the obtained solid particles are ammonium dimolybdate.

[0065] Example 6: A method for leaching molybdenum from molybdenum roasting ore, comprising the following steps: Step 1: Mix 50 g of molybdenum roasting ore and 16 g of ammonium bicarbonate to obtain a mixed material, place the mixed material in a sealed container and heat at 65 °C for 3.5 h to obtain the transformed material; Step 2: Place 50 g of the transformed material in 0.15 L of water, leach at 90 °C for 2 h, filter, add 1.5 g of ammonium sulfide (containing S 2- 8%) and let it stand for impurity removal, then filter to obtain molybdenum-containing solution A and leaching residue.

[0066] Step 3: Add 0.02 L of ammonium bicarbonate solution with a concentration of 1.50 mol / L to the molybdenum-containing solution A to adjust the pH value to 6.6, then heat to 95 °C and evaporate to crystallize for 3 h, filter, and the obtained solid particles are ammonium dimolybdate.

[0067] Example 7: A method for leaching molybdenum from molybdenum roasting ore, comprising the following steps: Step 1: Mix 50 g of molybdenum roasting ore and 10 g of ammonium carbonate to obtain a mixed material, place the mixed material in a sealed container and heat at 70 °C for 5 h to obtain the transformed material; Step 2: Place 50 g of the transformed material in 0.4 L of water, leach at 100 °C for 3 h, filter, add 0.3 g of hydrogen sulfide and let it stand for impurity removal, then filter to obtain molybdenum-containing solution A and leaching residue.

[0068] Step 3: Add 0.004 L of nitric acid solution with a concentration of 1.0 mol / L to the molybdenum-containing solution A to adjust the pH value to 2.5, then heat to 30 °C and crystallize for 1 h, filter, and the obtained solid particles are ammonium tetramolybdate.

[0069] Figure 8 XRD pattern of the solid particles prepared in Step 3 of Example 7, from Figure 8 It can be seen that the solid particles prepared in Example 3 are mainly ammonium tetramolybdate.

[0070] Figure 9 SEM image of the solid particles prepared in Step 3 of Example 7, from Figure 9It can be seen that the solid particles prepared in Example 3 are needle-shaped, with consistent particle morphology and uniform distribution.

[0071] Example 8: A method for leaching molybdenum from molybdenum roaster, comprising the following steps: Step 1, mix 50 g of molybdenum roaster and 8.5 g of ammonium carbonate to obtain a mixed material, place the mixed material in a closed container and heat at 50 °C for 3 h to obtain a transformed material; Step 2, place 50 g of the transformed material in 0.4 L of water, leach at 50 °C for 3 h, filter, add 0.3 g of hydrogen sulfide and let stand for impurity removal, filter, to obtain molybdenum-containing solution A and leaching residue.

[0072] Step 3, add 0.003 L of nitric acid solution with a concentration of 1.0 mol / L to the molybdenum-containing solution A to adjust the pH value to 2, then raise the temperature to 35 °C and crystallize for 1 h, filter, and the obtained solid particles are ammonium tetramolybdate.

[0073] Example 9: A method for leaching molybdenum from molybdenum roaster, comprising the following steps: Step 1, mix 50 g of molybdenum roaster and 10.5 g of ammonium carbonate to obtain a mixed material, place the mixed material in a closed container and heat at 60 °C for 2 h to obtain a transformed material; Step 2, place 50 g of the transformed material in 0.4 L of water, leach at 60 °C for 2.5 h, filter, add 0.3 g of hydrogen sulfide and let stand for impurity removal, filter, to obtain molybdenum-containing solution A and leaching residue.

[0074] Step 3, add 0.003 L of nitric acid solution with a concentration of 1.0 mol / L to the molybdenum-containing solution A to adjust the pH value to 4, then raise the temperature to 45 °C and crystallize for 1 h, filter, and the obtained solid particles are ammonium tetramolybdate.

[0075] Example 10: A method for leaching molybdenum from molybdenum roaster, comprising the following steps: Step 1, mix 50 g of molybdenum roaster and 12 g of ammonium carbonate to obtain a mixed material, place the mixed material in a closed container and heat at 75 °C for 3 h to obtain a transformed material; Step 2, place 50 g of the transformed material in 0.2 L of water, leach at 70 °C for 2 h, filter, add 0.2 g of hydrogen sulfide and let stand for impurity removal, filter, to obtain molybdenum-containing solution A and leaching residue.

[0076] Step 3, heat the molybdenum-containing solution A obtained in Step 2 to 90 °C and crystallize for 4 h, filter, and the obtained solid particles are ammonium dimolybdate.

[0077] Figure 10 XRD pattern of the transformed material prepared in Step 1 of Example 10, by Figure 10It can be seen that MoO₂ in molybdenum calcine has been transformed into (NH₄)₂Mo₂O₇.

[0078] Figure 11 XRD pattern of the leaching residue obtained in Step 2 of Example 10. It can be Figure 11 seen that there is basically no (NH₄)₂Mo₂O₇ in the leaching residue, which proves from the side that the molybdenum leaching rate of the method provided by the present invention is high.

[0079] Example 11: A method for leaching molybdenum from molybdenum calcine, comprising the following steps: Step 1, mix 50 g of molybdenum calcine and 11.5 g of ammonium carbonate to obtain a mixed material, place the mixed material in a closed container and heat it at 50 °C for 0.5 h to obtain a transformed material; Step 2, place 50 g of the transformed material in 0.2 L of water, leach at 70 °C for 2 h, filter, add 0.2 g of hydrogen sulfide and let it stand for impurity removal, filter to obtain a molybdenum-containing solution A and a leaching residue.

[0080] Step 3, heat the molybdenum-containing solution A obtained in Step 2 to 85 °C for crystallization for 3 h, filter, and the obtained solid particles are ammonium dimolybdate.

[0081] Example 12: A method for leaching molybdenum from molybdenum calcine, comprising the following steps: Step 1, mix 50 g of molybdenum calcine and 15 g of ammonium carbonate to obtain a mixed material, place the mixed material in a closed container and heat it at 75 °C for 3 h to obtain a transformed material; Step 2, place 50 g of the transformed material in 0.2 L of water, leach at 70 °C for 2 h, filter, add 0.2 g of hydrogen sulfide and let it stand for impurity removal, filter to obtain a molybdenum-containing solution A and a leaching residue.

[0082] Step 3, heat the molybdenum-containing solution A obtained in Step 2 to 100 °C for crystallization for 2 h, filter, and the obtained solid particles are ammonium dimolybdate.

[0083] Example 13: A method for leaching molybdenum from molybdenum calcine, comprising the following steps: Step 1, mix 50 g of molybdenum calcine and 19 g of ammonium bicarbonate to obtain a mixed material, place the mixed material in a closed container and heat it at 50 °C for 0.5 h to obtain a transformed material; Step 2, place 50 g of the transformed material in 0.1 L of water, leach at 70 °C for 2 h, filter, add 1 g of ammonium sulfide (containing S 2- 8%) and let it stand for impurity removal, filter to obtain a molybdenum-containing solution A and a leaching residue.

[0084] Step 3: Add 0.001 L of nitric acid solution with a concentration of 0.1 mol / L to the molybdenum-containing solution A to adjust the pH value to 5.5, then heat to 65 °C for crystallization for 2 h, and filter. The obtained solid particles are ammonium heptamolybdate.

[0085] Example 14: A method for leaching molybdenum from molybdenum calcine, comprising the following steps: Step 1: Mix 50 g of molybdenum calcine and 20 g of ammonium bicarbonate to obtain a mixed material. Place the mixed material in a sealed container and heat at 80 °C for 1 h to obtain a transformed material; Step 2: Place 50 g of the transformed material in 0.1 L of water, leach at 50 °C for 2 h, filter, add 1 g of ammonium sulfide (containing S 2- 8%) and let stand for impurity removal, then filter to obtain a molybdenum-containing solution A and leaching residues.

[0086] Step 3: Add 0.0015 L of nitric acid solution with a concentration of 0.1 mol / L to the molybdenum-containing solution A to adjust the pH value to 5.5, then heat to 55 °C for crystallization for 2 h, and filter. The obtained solid particles are ammonium heptamolybdate.

[0087] Example 15: A method for leaching molybdenum from molybdenum calcine, comprising the following steps: Step 1: Mix 50 g of molybdenum calcine and 24.5 g of ammonium bicarbonate to obtain a mixed material. Place the mixed material in a sealed container and heat at 65 °C for 0.5 h to obtain a transformed material; Step 2: Place 50 g of the transformed material in 0.1 L of water, leach at 60 °C for 3 h, filter, add 1 g of ammonium sulfide (containing S 2- 8%) and let stand for impurity removal, then filter to obtain a molybdenum-containing solution A and leaching residues.

[0088] Step 3: Add 0.003 L of nitric acid solution with a concentration of 0.1 mol / L to the molybdenum-containing solution A to adjust the pH value to 5.5, then heat to 65 °C for crystallization for 2 h, and filter. The obtained solid particles are ammonium heptamolybdate.

[0089] Example 16: A method for leaching molybdenum from molybdenum calcine, comprising the following steps: Step 1: Mix 50 g of molybdenum calcine and 10.5 g of ammonium carbonate to obtain a mixed material. Place the mixed material in a sealed container and heat at 100 °C for 5 h to obtain a transformed material; Step 2: Place 50 g of the transformed material in 0.3 L of water, leach at 70 °C for 2 h, filter, add 2.5 g of ammonium sulfide (containing S 2- 8%) and let stand for impurity removal, then filter to obtain a molybdenum-containing solution A and leaching residues.

[0090] Step 3: Add 0.003 L of hydrochloric acid solution with a concentration of 1.0 mol / L to the molybdenum-containing solution to adjust the pH value to 3.0, then heat to 35 °C for crystallization for 2 h, and filter. The obtained solid particles are ammonium tetramolybdate.

[0091] Example 17: A method for leaching molybdenum from molybdenum calcine, comprising the following steps: Step 1: Mix 50 g of molybdenum calcine and 11.5 g of ammonium carbonate to obtain a mixed material. Place the mixed material in a sealed container and heat at 100 °C for 5 h to obtain a transformed material; Step 2: Place 50 g of the transformed material in 0.3 L of water, leach at 70 °C for 2 h, filter, add 2.5 g of ammonium sulfide (containing S 2- 8%) and let stand for impurity removal, then filter to obtain a molybdenum-containing solution A and leaching residue.

[0092] Step 3: Add 0.004 L of hydrochloric acid solution with a concentration of 1.0 mol / L to the molybdenum-containing solution to adjust the pH value to 3.0, then heat to 35 °C for crystallization for 2 h, and filter. The obtained solid particles are ammonium tetramolybdate.

[0093] Example 18: A method for leaching molybdenum from molybdenum calcine, comprising the following steps: Step 1: Mix 50 g of molybdenum calcine and 15 g of ammonium carbonate to obtain a mixed material. Place the mixed material in a sealed container and heat at 100 °C for 5 h to obtain a transformed material; Step 2: Place 50 g of the transformed material in 0.3 L of water, leach at 70 °C for 2 h, filter, add 2.5 g of ammonium sulfide (containing S 2- 8%) and let stand for impurity removal, then filter to obtain a molybdenum-containing solution A and leaching residue.

[0094] Step 3: Add 0.005 L of hydrochloric acid solution with a concentration of 1.0 mol / L to the molybdenum-containing solution to adjust the pH value to 3.0, then heat to 35 °C for crystallization for 2 h, and filter. The obtained solid particles are ammonium tetramolybdate.

[0095] It can be seen from the crystallization processes of Examples 1 to 18 that in the crystallization process of the molybdenum-containing solution obtained by the method provided by the present invention, the target product can be crystallized without adding or only adding a small amount of acid or ammonium salt.

[0096] Comparative Example 1: Direct leaching with ammonia water A method for leaching molybdenum from molybdenum calcine, comprising the following steps: Step 1: Add 50 g of molybdenum calcine to 0.16 L of ammonia water solution with an ammonia concentration of 22 g / L, leach at 70 °C for 1 h, and then filter to obtain a molybdenum-containing solution A and leaching residue.

[0097] Step 2: Heat the molybdenum-containing solution A to 70 °C and evaporate to crystallize for 5 h, then filter. The solid particles obtained are ammonium heptamolybdate.

[0098] Comparative Example 2: Mix ammonium bicarbonate, molybdenum roasted ore and water, and directly leach. A method for leaching molybdenum from molybdenum roasted ore, comprising the following steps: Step 1: Add 50 g of molybdenum roasted ore and 19 g of ammonium bicarbonate to 0.2 L of water, stir at 80 °C for 60 min, then filter to obtain a molybdenum-containing solution A and leaching residue.

[0099] Step 2: Heat the molybdenum-containing solution A to 90 °C and evaporate to crystallize for 5 h, then filter. The solid particles obtained are ammonium dimolybdate.

[0100] Calculate the leaching rate of MoO3 in some examples and comparative examples. The leaching rate of MoO3 = mass of molybdenum oxide in the solution / (weight of molybdenum roasted ore × 72.54 wt.%) %.

[0101] Table 1 Weight of leaching residue and leaching rate of MoO3 in Step 1 of some examples and Comparative Examples 1-2 provided by the present invention As can be seen from Table 1, the leaching rate of MoO3 in the transformation leaching process provided by the present invention is stably > 95%, which can further prove that the transformation leaching process provided by the present invention has a high utilization rate of MoO3 and can reduce production costs.

[0102] By comparing Example 1 with Comparative Example 1 and Comparative Example 2 respectively, it can be seen that the transformation leaching process provided by the present invention has a higher leaching rate of MoO3.

[0103] The above embodiments are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope of the present invention, according to the technical solution and its concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A method for leaching molybdenum from molybdenum roasted sand, characterized in that, The steps include: Step 1, mixing molybdenum calcined sand and solid ammonium source and heating to obtain a transition material; Step 2: soaking the transformed material in water and filtering to obtain a molybdenum-containing solution A.

2. The method for leaching molybdenum from molybdenum calcined sand as claimed in claim 1, wherein In step 1, the solid ammonium source is any one or both of ammonium carbonate and ammonium bicarbonate.

3. The method for leaching molybdenum from molybdenum calcined sand as claimed in claim 1, wherein The main component of the molybdenum-containing solution A obtained in step 2 is ammonium heptamolybdate or ammonium dimolybdate.

4. The method for leaching molybdenum from molybdenum calcined sand as claimed in claim 3, wherein In step 1, MoO3 in molybdenum roasted sand and NH4 in ammonium source + When the molar ratio is 1:0.7~0.9, the main component of the molybdenum-containing solution A is ammonium heptamolybdate; MoO3 in the molybdenum calcined sand and NH4 in the ammonium source + When the molar ratio of molybdenum to molybdenum is 1:0.95~1.25, the main component of the molybdenum-containing solution A is ammonium dimolybdate.

5. The method for leaching molybdenum from molybdenum calcined sand as claimed in claim 3, wherein After step 2, a crystallization process is also included.

6. The method for leaching molybdenum from molybdenum calcine as claimed in claim 5, wherein The ammonium heptamolybdate solution is evaporated and crystallized, and then filtered to obtain solid particles of ammonium heptamolybdate; an ammonium source is added to the ammonium heptamolybdate solution to adjust the pH value of the reaction system to 5.9-6.6, and then evaporated, crystallized, and filtered to obtain solid particles of ammonium dimolybdate; an acid solution is added to the ammonium heptamolybdate solution to adjust the pH value of the reaction system to 2-4, and the reaction system is allowed to stand and filtered to obtain solid particles of ammonium tetramolybdate.

7. The method for leaching molybdenum from molybdenum calcine as claimed in claim 6, wherein The ammonium source is any one or more of ammonium carbonate, ammonium bicarbonate, ammonium orthomolybdate and ammonia water.

8. The method for leaching molybdenum from molybdenum calcined sand as claimed in claim 5, wherein The ammonium dimolybdate solution is evaporated and crystallized to obtain solid particles of ammonium dimolybdate; an acid solution is added to the ammonium dimolybdate solution to adjust the pH value of the reaction system to 5.0-5.7, and then evaporated, crystallized, and filtered to obtain solid particles of ammonium dimolybdate; an acid solution is added to the filtered molybdenum-containing solution A to adjust the pH value of the reaction system to 2-4, let it stand, and filter to obtain solid particles of ammonium tetramolybdate.

9. The method for leaching molybdenum from molybdenum calcined sand according to claim 6 or 8, wherein The acid solution is any one or more of nitric acid, hydrochloric acid and sulfuric acid.

10. The method for leaching molybdenum from molybdenum calcine according to claim 6 or 8, wherein After obtaining the molybdenum-containing solution A and before crystallization, the method further includes an impurity removal process. During the impurity removal process, an impurity remover is added to the molybdenum-containing solution A; the impurity remover is any one or more of ammonium sulfide and hydrogen sulfide.

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