A method for processing molybdenite

Abstract

The present application belongs to the field of molybdenite smelting, and particularly relates to a molybdenite processing method. Molybdenite and an auxiliary agent are mixed and roasted to obtain roasted material. The auxiliary agent is magnesium oxide or a precursor capable of being converted into magnesium oxide in the roasting stage. The roasted material is treated by sulfuric acid leaching to obtain a leaching solution rich in molybdenum and magnesium. The leaching solution is then subjected to molybdenum-magnesium separation treatment to obtain a magnesium solution and a molybdenum solution. The present application can effectively improve the molybdenum recovery rate and significantly reduce the process residue rate in the processing stage.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of rare metal material preparation, in particular to a processing method of molybdenite. BACKGROUND

[0002] Molybdenite is the main raw material for molybdenum smelting. The mainstream process of molybdenum smelting is to convert molybdenite into molybdenum calcine (industrial molybdenum oxide) by oxidation roasting. Molybdenum calcine is mainly used as an additive in the steel industry, a raw material for producing molybdenum iron, and also a main raw material for producing ammonium molybdate. Ammonium molybdate is the most important molybdenum intermediate chemical, which is mainly produced by the classical process route of "molybdenum calcine ammonia leaching-solution purification-ammonium molybdate crystallization".

[0003] In the process of molybdenite oxidation roasting, since molybdenum trioxide, the roasting product, is easy to sublimate and volatilize in a high-temperature environment, and the oxidation of molybdenite is a strong exothermic reaction, a large amount of air needs to be introduced to regulate the temperature in the furnace, which often produces a large amount of low-concentration sulfur dioxide flue gas. Although low-concentration molybdenite roasting flue gas acid production has been successfully applied at present, there are still events of sulfur dioxide exceeding the standard, which indicates that there are still some problems in the low-concentration flue gas acid production system, and technical improvement is still needed. Therefore, the existing technology also provides some means to fix sulfur dioxide. However, most of the existing solutions can only achieve efficient recovery of Mo, and the sulfur in them is also discarded in the form of solid waste which is difficult to handle, and essentially does not solve the problem of sulfur emission. Moreover, a large amount of solid waste produced in the process will increase the difficulty of process treatment, and inevitably interfere with the extraction and recovery of molybdenum. SUMMARY

[0004] In view of the problems in the prior art, the present application aims to provide a processing method of molybdenite, which aims to achieve efficient utilization of molybdenum and sulfur in molybdenite, and reduce the three-waste output in the processing process.

[0005] A processing method of molybdenite, which comprises the following steps: mixing molybdenite and an additive to obtain a roasting material, wherein the additive is magnesium oxide or a precursor capable of being converted into magnesium oxide in the roasting stage;

[0006] The roasting material is subjected to sulfuric acid leaching treatment to obtain a leaching solution rich in molybdenum and magnesium, and then the leaching solution is subjected to molybdenum-magnesium separation treatment to obtain a magnesium solution and a molybdenum solution.

[0007] The application innovatively uses magnesium oxide as an auxiliary agent to assist molybdenite roasting, and innovatively uses its special chemical reaction mechanism and physical and chemical properties to realize the dual resource utilization of molybdenum and sulfur in molybdenite, and effectively avoid waste and waste residue in the leaching stage, avoid the influence of waste residue on molybdenum leaching, so as to help obtain excellent molybdenum extraction effect under lower auxiliary agent dosage and milder leaching conditions.

[0008] In the application, the grade of molybdenite is not particularly required, for example, the Mo grade can be above 3%, and further can be 20-50%.

[0009] In the application, the total molar ratio of Mg element in the auxiliary agent and sulfur and molybdenum elements in molybdenite is above 1, preferably 1.1-2.0:1, and further preferably 1.1-1.3:1. In the application, the effective transformation of sulfur and molybdenum in molybdenite can be effectively realized under lower auxiliary agent dosage.

[0010] In the application, the roasting process is carried out in an oxygen-containing atmosphere.

[0011] In the application, the roasting temperature is 400-700℃, further can be 450-600℃, and further preferably 500-560℃; in the application, due to the advantages of auxiliary roasting, it can realize good transformation and modification under relatively mild temperature, and further improve the solubility for subsequent leaching.

[0012] In the application, the roasting time is above 1h, and considering the preparation process efficiency, it can be further 1-4h.

[0013] In the application, due to the physical and chemical reaction mechanism of the magnesium oxide auxiliary agent roasting, the roasting product has excellent leaching behavior and structural characteristics, so excellent leaching can be realized under low acid system, and in addition, the output of slag can be effectively reduced.

[0014] In the application, in the sulfuric acid leaching stage, the concentration of the initial sulfuric acid solution is 1-4M; further can be 1.5-2M. In the application, due to the advantages of auxiliary roasting, it can realize co-leaching of Mo / Mg / S based on the composition dissolution behavior and acid conversion under mild conditions.

[0015] Preferably, the liquid-solid ratio of sulfuric acid and roasting material is above 1ml / g, preferably 1-5ml / g, and further preferably 2-4ml / g;

[0016] Preferably, the temperature in the sulfuric acid leaching stage is above 10℃, preferably 20-45℃, and further preferably 20-25℃;

[0017] Preferably, the time of sulfuric acid leaching is above 0.5h, and can be further preferred to be 0.5-4h, and further to be 1-2h in consideration of preparation efficiency.

[0018] In the present application, based on the roasting treatment of the magnesium oxide auxiliary agent, the molybdenum and sulfur in the molybdenite can be recovered into the leaching solution. In the present application, the selective separation of the molybdenum and magnesium sulfate can be realized based on ion exchange or extraction.

[0019] In the present application, the leaching solution is subjected to ion exchange treatment to obtain a magnesium solution, and the resin after ion exchange is subjected to desorption treatment to obtain a molybdenum solution.

[0020] In the present application, the resin used in the ion exchange stage can be known.

[0021] In the present application, the desorption agent in the desorption stage can be ammonia water.

[0022] In another separation method of molybdenum-magnesium in the present application, the leaching solution and the extraction organic phase are mixed for extraction treatment, the raffinate of extraction is the magnesium solution, and the loaded organic phase of extraction is subjected to back extraction to obtain the molybdenum solution.

[0023] The extractant in the extraction stage includes at least one of primary amine extractant and tertiary amine extractant.

[0024] The innovative research of the present application shows that the selective separation of molybdenum and magnesium sulfate can be unexpectedly realized by using the extractant for extraction treatment, which is beneficial to the high recovery of molybdenum and sulfur in molybdenite.

[0025] In the present application, the extractant is at least one of N235 and N1923.

[0026] Preferably, the content of the extractant in the extraction organic phase is above 5v%, and is preferably 5-30v%, and further can be 5-15v%; in the present application, the roasting conversion and modification advantages of the auxiliary agent are beneficial to improve the leaching behavior, and further cooperate with the subsequent extraction method, so that the advantages of extraction effect and extraction selectivity can be unexpectedly obtained under the conditions of more moderate and lower extraction content.

[0027] In the present application, the extraction organic phase can also be allowed to add a modifier, such as secondary octanol, and the content thereof can be adjusted according to conventional cognition, for example, can be 1-20v%, and further can be 5-15v%. The hydrophobic diluent therein can be sulfonated kerosene.

[0028] Preferably, the O / A of the extraction stage is 1-10:1, further can be 2-5:1, the contact time is above 1 min, preferably 1-10 min, further can be 4-6 min;

[0029] Preferably, the stripping agent of the stripping stage is ammonia water;

[0030] The amount of ammonia water used in the stripping stage is not less than the theoretical amount, preferably, the O / A of the stripping stage is 1-10:1, the contact time is above 1 min, preferably 1-20 min, further can be 5-15 min.

[0031] In the present application, the obtained magnesium liquid is treated by evaporation crystallization, and magnesium sulfate crystals are obtained by filtration.

[0032] In the present application, the molybdenum liquid is treated by impurity removal to obtain purified molybdenum liquid, and then treated by acid precipitation to obtain ammonium tetramolybdate product;

[0033] Preferably, the impurity removal method is ammonium magnesium salt precipitation;

[0034] Preferably, the process of the impurity removal stage is: using sulfuric acid to control the pH of the molybdenum liquid to 9-10, then adding magnesium sulfate for precipitation treatment, and then treating by solid-liquid separation to obtain purified molybdenum liquid;

[0035] Preferably, the magnesium sulfate is the magnesium sulfate crystal obtained by evaporation crystallization of the magnesium liquid;

[0036] Preferably, the ratio of the amount of magnesium sulfate to the total molar amount of phosphorus and arsenic in the molybdenum liquid is 1-1.5:1;

[0037] Preferably, the temperature of the impurity removal stage is above 20℃, preferably 20-60℃, further preferably 25-50℃;

[0038] Preferably, the time of the impurity removal stage is above 0.5h, preferably 0.5-6h, preferably 0.5-4h.

[0039] Preferably, the acid used in the acid precipitation stage is nitric acid;

[0040] Preferably, the pH of the acid precipitation stage is less than or equal to 3, preferably 1-2;

[0041] Preferably, the temperature of the acid precipitation stage is above 20℃, preferably 50-60℃;

[0042] Preferably, the time of the acid precipitation stage is above 0.5h, preferably 0.5-4h.

[0043] Beneficial effects

[0044] 1. The application innovatively uses magnesium oxide as an auxiliary agent to assist the roasting treatment of molybdenite, which can unexpectedly realize high-value utilization of molybdenum and sulfur in molybdenite, avoid process hazardous solid waste, and avoid the influence of waste slag on molybdenum extraction.

[0045] 2. The auxiliary roasting process disclosed by the application can obtain excellent molybdenum and sulfur combined leaching extraction effect under lower material consumption and milder conditions based on its special transformation mechanism and physicochemical modification characteristics.

[0046] 3. In the application, Mo and S in molybdenite can be efficiently leached together, and based on the extraction of the primary amine extractant and the tertiary amine extractant, high-selectivity extraction and separation of molybdenum and magnesium can be unexpectedly realized. DETAILED DESCRIPTION

[0047] The following examples are further described in conjunction with the application, which are intended to illustrate the application rather than further limit the application.

[0048] The molybdenum ore processing method disclosed by the application comprises the following steps:

[0049] S1. Roasting

[0050] The magnesium oxide is mixed with the molybdenite and then roasted.

[0051] S2. Leaching

[0052] The roasted material produced in step S1 is subjected to acid leaching, and a leaching solution containing molybdenum and magnesium sulfate, and a small amount of insoluble residue (which is a residue component other than molybdenite MoS2, and is not a MoS2 process residue) are obtained by filtration.

[0053] S3. Molybdenum extraction and transformation

[0054] Molybdenum is extracted from the molybdenum and magnesium sulfate-containing leaching solution in step S2 by ion exchange or solvent extraction, and ammonium molybdate solution is obtained by ammonia transformation, and a magnesium sulfate-containing post-exchange solution or raffinate is obtained.

[0055] S4. Preparation of magnesium salt by-product

[0056] Magnesium salt crystals are prepared from the magnesium sulfate-containing post-exchange solution or raffinate produced in step S3 by evaporation crystallization.

[0057] S5. Purification of ammonium molybdate solution

[0058] The crude ammonium molybdate solution obtained in step S3 is adjusted to a pH of 9.0-10.0 with sulfuric acid, and then ammonium magnesium salt precipitation method is used to remove impurities such as phosphorus and arsenic, and the magnesium salt purifying agent used is the magnesium sulfate produced in step S4.

[0059] S6. Preparation of ammonium tetramolybdate product

[0060] The ammonium molybdate solution purified in step S5 is used to prepare ammonium tetramolybdate product by nitric acid acid precipitation.

[0061] The total molar ratio of the amount of magnesium oxide added to the sulfur and molybdenum elements in the molybdenite is 1.1-2.0:1, the roasting temperature is 400-700°C, and the roasting time is 1-4h. The S1 roasting stage is carried out in an air atmosphere.

[0062] In step S2, the leaching agent used is sulfuric acid, the sulfuric acid concentration is 1-4mol / L, the liquid-solid ratio is 1-5:1 (mL / g), the leaching temperature is 20-45°C, and the leaching time is 0.5-4h.

[0063] In step S3, the resin used is a macroporous weakly basic anion exchange resin, and the extractant used is a primary amine or tertiary amine extractant.

[0064] In step S4, the ion exchange solution or raffinate is evaporated to 1 / 2-1 / 4 of the original volume by evaporation concentration, and then filtered after cooling to room temperature to obtain magnesium sulfate crystals.

[0065] In step S5, the total molar ratio of the amount of purifying agent magnesium sulfate added to the total amount of impurities phosphorus and arsenic in the solution is 1.1-1.5:1, the reaction temperature is 20-60°C, and the reaction time is 0.5-6h.

[0066] In step S6, a sulfuric acid solution with a concentration of 15-35wt% is added to adjust the pH to 1.5-2.0, the reaction temperature is 50-60°C, and the reaction time is 0.5-4h.

[0067] The following is a typical case:

[0068] Example 1

[0069] S1. Roasting

[0070] 100g of molybdenite (containing Mo 38.23%, S 36.15%, SiO2 6.12%, P 0.16%, As 0.02%) was mixed with magnesium oxide, the total molar ratio of the amount of magnesium oxide added to the sulfur and molybdenum elements in the molybdenite was 1.1:1, and roasting was carried out at 700°C for 1h.

[0071] S2. Acid leaching

[0072] The roasting material produced in step S1 was subjected to leaching reaction using sulfuric acid, the sulfuric acid concentration was 4mol / L, the liquid-solid ratio was 2:1 (ml / g), the leaching temperature was 45°C, and the leaching time was 3h. After the leaching was completed, the molybdenum leaching rate was 99.2%, and the residue rate was 11.3%.

[0073] S3. Molybdenum extraction and transformation

[0074] The molybdenum was extracted from the leaching solution containing molybdenum and magnesium sulfate generated in step S2 by static adsorption using 100 ml D301 resin, and the Mo concentration in the exchanged solution was 0.09 g / L, and the molybdenum adsorption rate was 99.9%; desorption was performed using 5 mol / L ammonia water, the ammonia water amount was 3 times the theoretical amount, the single-stage desorption rate was 97.2%, and a crude ammonium molybdate solution was obtained.

[0075] S4. Preparation of magnesium salt by-product

[0076] The magnesium sulfate-containing exchanged solution generated in step S3 was prepared by evaporation crystallization, and when the evaporation was performed to 1 / 3 of the volume of the exchanged solution, the crystallization rate of magnesium sulfate was 92.2% after cooling to room temperature.

[0077] S5. Purification of ammonium molybdate solution

[0078] First, the crude ammonium molybdate solution obtained in step S3 was adjusted to pH 9.0 with sulfuric acid, then the magnesium sulfate crystals produced in step S4 were dissolved to prepare a 100 g / L solution, and then the solution was added dropwise into the crude ammonium molybdate solution which had been adjusted, the ratio of the amount of magnesium sulfate added to the total molar amount of impurities phosphorus and arsenic in the solution was 1.1, the reaction temperature was 25°C, and the reaction time was 4 h. After the reaction was completed, the purified ammonium molybdate solution was obtained by filtration.

[0079] S6. Preparation of ammonium tetramolybdate product

[0080] A 15wt% nitric acid solution was added to the ammonium molybdate solution purified in step S5, the solution pH was adjusted to 1.5, the reaction temperature was 50°C, and after aging for 4 h, the ammonium tetramolybdate product was obtained by filtration.

[0081] Example 2

[0082] S1. Roasting

[0083] 100 g of molybdenite (containing Mo 38.23%, S 36.15%, SiO2 6.12%, P 0.16%, and As 0.02%) was mixed with magnesium oxide, the amount of magnesium oxide was 1.5:1 of the total molar amount of sulfur and molybdenum in the molybdenite, and the mixture was roasted at 700°C for 2 h.

[0084] S2. Acid leaching

[0085] The roasted material produced in step S1 was subjected to leaching reaction using sulfuric acid, the sulfuric acid concentration was 3 mol / L, the liquid-solid ratio was 3:1 (ml / g), the leaching temperature was 20°C, and the leaching time was 4 h. After the leaching was completed, the molybdenum leaching rate was 99.4%, and the residue rate was 11.0%.

[0086] S3. Extraction and transformation of molybdenum

[0087] The molybdenum was extracted from the leaching solution containing molybdenum and magnesium sulfate produced in step S2 by static adsorption using 100 ml D314 resin. The Mo concentration in the exchanged solution was 0.08 g / L, and the molybdenum adsorption rate was 99.9%. Desorption was carried out using 5 mol / L ammonia water, and the amount of ammonia water used was 3 times the theoretical amount. The single-stage desorption rate was 96.8%, and a crude ammonium molybdate solution was obtained.

[0088] S4. Preparation of magnesium salt by-product

[0089] Magnesium sulfate was prepared from the exchanged solution containing magnesium sulfate produced in step S3 by evaporation crystallization. When the volume of the exchanged solution was reduced to 1 / 2, the crystallization rate of magnesium sulfate was 83.2% as measured after cooling to room temperature.

[0090] S5. Purification of ammonium molybdate solution

[0091] First, the crude ammonium molybdate solution obtained in step S3 was adjusted to pH 10.0 using sulfuric acid. Then, the magnesium sulfate crystals produced in step S4 were dissolved to prepare a 100 g / L solution, which was then added dropwise to the adjusted crude ammonium molybdate solution. The ratio of the amount of magnesium sulfate added to the total molar amount of impurities phosphorus and arsenic in the solution was 1.5, and the reaction temperature was 50°C. The reaction time was 0.5 h. After the reaction was completed, the purified ammonium molybdate solution was obtained by filtration.

[0092] S6. Preparation of ammonium tetramolybdate product

[0093] A 35 wt% nitric acid solution was added to the purified ammonium molybdate solution obtained in step S5, and the pH of the solution was adjusted to 2.0. The reaction temperature was 60°C, and the solution was aged for 0.5 h before being filtered to obtain the ammonium tetramolybdate product.

[0094] Example 3

[0095] S1. Roasting

[0096] 100 g of molybdenite (containing Mo 38.23%, S 36.15%, SiO2 6.12%, P 0.16%, and As 0.02%) was mixed with magnesium oxide. The amount of magnesium oxide used was 2.0:1 relative to the total molar amount of sulfur and molybdenum in the molybdenite, and the mixture was roasted at 600°C for 4 h.

[0097] S2. Acid leaching

[0098] The roasted material produced in step S1 was subjected to a leaching reaction using sulfuric acid. The sulfuric acid concentration was 2 mol / L, the liquid-solid ratio was 5:1 (ml / g), the leaching temperature was 40°C, and the leaching time was 3 h. After the leaching was completed, the molybdenum leaching rate was 99.3%, and the residue rate was 13.4%.

[0099] S3. Extraction and transformation of molybdenum

[0100] The molybdenum-containing and magnesium sulfate-containing leaching solution produced in step S2 was extracted with 500 ml of organic phase (10 v% N235 (extractant) + 10 v% sec-octanol + 80 v% sulfonated kerosene) at room temperature for 10 min; the water washing condition was O / A = 5:1 for 5 min; the stripping condition was ammonia water stripping with ammonia water concentration of 5 mol / L, O / A phase ratio of 1:1, and time of 10 min. The Mo concentration in the raffinate was 0.05 g / L, the molybdenum extraction rate was 99.9%, and the extraction loss of Mg was less than 0.2%; the single-stage stripping rate was 98.8%, and a crude ammonium molybdate solution was obtained.

[0101] S4. Preparation of magnesium salt by-product

[0102] The magnesium sulfate-containing exchanged solution produced in step S3 was prepared by evaporation crystallization. When the evaporation was to 1 / 4 of the volume of the exchanged solution, the crystallization rate of magnesium sulfate was 95.7% after cooling to room temperature.

[0103] S5. Purification of ammonium molybdate solution

[0104] First, the crude ammonium molybdate solution obtained in step S3 was adjusted to pH 10.0 with sulfuric acid, and then the magnesium sulfate crystals produced in step S4 were dissolved to prepare a 100 g / L solution, which was then added dropwise into the crude ammonium molybdate solution that had been adjusted. The ratio of the amount of magnesium sulfate added to the total molar amount of impurities phosphorus and arsenic in the solution was 1.2:1, the reaction temperature was 50°C, and the reaction time was 0.5 h. After the reaction, the purified ammonium molybdate solution was obtained by filtration.

[0105] S6. Preparation of ammonium tetramolybdate product

[0106] A 35 wt% nitric acid solution was added to the purified ammonium molybdate solution from step S5, the solution pH was adjusted to 1.5, the reaction temperature was 60°C, and the ammonium tetramolybdate product was obtained by filtration after aging for 0.5 h.

[0107] Example 4

[0108] S1. Roasting

[0109] 100 g of molybdenite (containing Mo 38.23%, S 36.15%, SiO2 6.12%, P 0.16%, and As 0.02%) was mixed with magnesium oxide, and the molar ratio of the amount of magnesium oxide to the sulfur content in the molybdenite was 1.5:1. Roasting was performed at 550°C for 4 h.

[0110] S2. Acid leaching

[0111] The roasted material from step S1 was subjected to leaching reaction with sulfuric acid, the concentration of sulfuric acid (acid liquor) was 1.5 mol / L, the liquid-solid ratio was 3:1 (ml / g), the leaching temperature was 25℃, and the leaching time was 1 h. After the leaching was completed, the analysis of molybdenum leaching rate was 99.5%, and the residue rate was 13.1%.

[0112] S3. Extraction and transformation of molybdenum

[0113] The molybdenum-containing and magnesium sulfate-containing leaching solution produced in step S2 was extracted with 500 ml of organic phase (10v% N1923 + 10v% sec-octanol + 80v% sulfonated kerosene) at room temperature, the contact time was 10 min; the water washing condition was O / A = 5:1, the contact time was 5 min; the stripping condition was ammonia water stripping, the ammonia water concentration was 5 mol / L, the phase ratio O / A was 1:1, and the time was 10 min. The Mo concentration in the raffinate was 0.03 g / L, the molybdenum extraction rate was 99.9%, and the extraction loss of Mg was less than 0.2%; the single-stage stripping rate was 96.4%, and a crude ammonium molybdate solution was obtained.

[0114] S4. Preparation of magnesium salt by-product

[0115] Magnesium sulfate was prepared from the exchanged solution containing magnesium sulfate produced in step S3 by evaporation crystallization. When the evaporation was to 1 / 3 of the volume of the exchanged solution, the magnesium sulfate crystallization rate was 93.1% after cooling to room temperature.

[0116] S5. Purification of ammonium molybdate solution

[0117] First, the crude ammonium molybdate solution obtained in step S3 was adjusted to pH 10.0 with sulfuric acid, then the magnesium sulfate crystals produced in step S4 were dissolved in water to prepare a 100 g / L solution, and then added dropwise into the crude ammonium molybdate solution which had been adjusted, the ratio of the amount of magnesium sulfate added to the total molar amount of impurities phosphorus and arsenic in the solution was 1.1:1, the reaction temperature was 50℃, and the reaction time was 1 h. After the reaction was completed, the purified ammonium molybdate solution was obtained by filtration.

[0118] S6. Preparation of ammonium tetramolybdate product

[0119] A 35wt% nitric acid solution was added to the purified ammonium molybdate solution from step S5, the solution pH was adjusted to 1.5, the reaction temperature was 50℃, and the aging time was 2 h, then the ammonium tetramolybdate product was obtained by filtration.

[0120] Comparative Example 1

[0121] Compared with Example 4, the only difference was that in S1, equal molar calcium hydroxide was used instead of magnesium oxide for roasting, and other operations and parameters were the same as those in Example 4.

[0122] In this case S2, after the leaching was completed, the analysis of molybdenum leaching rate was 75.3%, and the residue rate was 184.1%.

[0123] Comparative Example 2

[0124] Compared with Example 4, the difference is only that in S1, the magnesium oxide is replaced by equal moles of calcium hydroxide for calcination, and in S2, 3M HCl is used as the acid solution for mild leaching, and other operations and parameters are the same as those in Example 4.

[0125] In the case of S2, after the leaching is completed, the molybdenum leaching rate is 76.1%, and the residue rate is 180.2%.

[0126] Comparative Example 3

[0127] Compared with Example 4, the difference is only that in S3, equal volume of P507 is used to replace N1923 therein, and other operations and parameters are the same as those in Comparative Example 2.

[0128] The results show that in S3, the molybdenum extraction rate is 65.1%, the magnesium ion extraction rate is 42.4%, the molybdenum single-stage stripping rate is 95.4%, and a crude ammonium molybdate solution is obtained.

[0129] It can be seen that for the molybdenum-magnesium sulfuric acid system of the application, the use of the extraction conditions innovatively enables the selective extraction and separation of Mo-Mg to be unexpectedly achieved.

Claims

1. A method for processing molybdenite, characterized in that, The roasting feed is obtained by mixing molybdenite and an additive and roasting it. The additive is magnesium oxide or a precursor that can be converted into magnesium oxide during the roasting stage. The roasting process is carried out in an oxygen-containing atmosphere. The roasted material was treated with sulfuric acid leaching to obtain a leachate enriched with molybdenum and magnesium. The leachate was then subjected to molybdenum-magnesium separation treatment to obtain magnesium solution and molybdenum solution. The total molar ratio of Mg in the additive to sulfur and molybdenum in molybdenite is greater than 1; The roasting temperature is 400~700℃; The leachate was subjected to ion exchange treatment to obtain a magnesium solution, and the exchanged resin was then desorbed to obtain a molybdenum solution; the desorbent in the desorption stage was ammonia. The leachate and the extracting organic phase are mixed for extraction. The raffinate is the magnesium solution. The extracted loaded organic phase is back-extracted to obtain the molybdenum solution. The extractant used in the extraction stage is at least one of N235 and N1923.

2. The method for processing molybdenite as described in claim 1, characterized in that, The total molar ratio of Mg in the additive to sulfur and molybdenum in molybdenite is 1.1~2.0:

1.

3. The method for processing molybdenite as described in claim 2, characterized in that, The total molar ratio of Mg in the additive to sulfur and molybdenum in molybdenite is 1.1~1.3:

1.

4. The method for processing molybdenite as described in claim 1, characterized in that, The roasting time is more than 1 hour.

5. The method for processing molybdenite as described in claim 1, characterized in that, The roasting time is 1 to 4 hours.

6. The method for processing molybdenite as described in claim 1, characterized in that, During the sulfuric acid leaching stage, the initial concentration of the sulfuric acid solution is 1~4M; The liquid-to-solid ratio of sulfuric acid and calcined material is above 1 mL / g; The temperature during the sulfuric acid leaching stage is above 10℃; The sulfuric acid leaching time is more than 0.5 hours.

7. The method for processing molybdenite as described in claim 6, characterized in that, The liquid-to-solid ratio of sulfuric acid and calcined material is 1~5 mL / g; The temperature during the sulfuric acid leaching stage is 20~45℃; The sulfuric acid leaching time is 0.5~4 hours.

8. The method for processing molybdenite as described in claim 1, characterized in that, In the extracted organic phase, the content of the extractant is above 5% v. During the extraction stage, the O / A ratio is 1~10:1, and the contact time is more than 1 minute. The stripping agent in the stripping stage is ammonia. During the back-extraction stage, the O / A ratio is 1~10:1, and the contact time is more than 1 minute.

9. The method for processing molybdenite as described in claim 8, characterized in that, In the extracted organic phase, the content of the extractant is 5-30% v%. The contact time during the extraction stage is 1-10 minutes; The contact time during the back-extraction stage is 1 to 20 minutes.

10. The method for processing molybdenite according to any one of claims 1 to 9, characterized in that, The obtained magnesium solution was subjected to evaporation and crystallization treatment, and then filtered to obtain magnesium sulfate crystals.

11. The method for processing molybdenite according to any one of claims 1 to 9, characterized in that, The molybdenum solution was purified by removing impurities; then, it was acid-precipitated to obtain ammonium tetramolybdate product. The impurity removal method is ammonium magnesium salt precipitation; The impurity removal process is as follows: sulfuric acid is used to adjust the pH of the molybdenum solution to 9-10, followed by the addition of magnesium sulfate for precipitation treatment, and then solid-liquid separation treatment to obtain purified molybdenum solution; The magnesium sulfate mentioned is magnesium sulfate crystal obtained by evaporation and crystallization of magnesium liquid; The ratio of magnesium sulfate dosage to the total molar amount of phosphorus and arsenic in the molybdenum solution is 1~1.5:1; The temperature during the impurity removal stage is above 20℃; The impurity removal stage takes more than 0.5 hours.

12. The method for processing molybdenite as described in claim 11, characterized in that, The temperature during the impurity removal stage is 20~60℃; The impurity removal stage lasts for 0.5 to 6 hours.

13. The method for processing molybdenite as described in claim 11, characterized in that, The acid used in the acid precipitation stage is nitric acid; The pH during the acid precipitation stage is less than or equal to 3; The temperature during the acid precipitation stage is above 20℃; The acid precipitation stage should last for more than 0.5 hours.

14. The method for processing molybdenite as described in claim 13, characterized in that... The pH during the acid precipitation stage is 1-2; The temperature during the acid precipitation stage is 50~60℃; The acid precipitation stage lasts for 0.5 to 4 hours.