CN102557033B - Process for recovering molybdenum-silicon heteropoly acid from waste molybdenum disilicide - Google Patents

Abstract

The invention discloses a process for recovering molybdenum silicon heteropolyacid from waste molybdenum disilicide, which belongs to the technical field of solid waste recovery and utilization. The waste molybdenum disilicide is crushed into powder, then the waste molybdenum disilicide powder is transferred into a porcelain boat, roasted at a certain temperature to obtain a mixed powder of molybdenum and silicon oxide, and the oxidized powder is mixed with deionized water to produce Slurry; add solid NaOH to the slurry, stir magnetically, filter after cooling, pour the filtered solution directly into hydrochloric acid for stirring, then put it into a water bath for heating, and keep stirring until silica gel is precipitated, filter silica gel, Add n-butanol to the filtrate for extraction, and carry out vacuum distillation to obtain the crude product of molybdenum silica heteropoly acid; dissolve it in deionized water, add a small amount of nitric acid, filter and wash off the residual n-butanol organic matter, and dry to obtain molybdenum silica heteropoly acid acid. The advantage is that molybdenum in waste molybdenum disilicide can be reused, raw materials are saved, and resource recycling is realized.

Description

A process for recovering molybdenum silicon heteropolyacid from waste molybdenum disilicide

technical field

The invention belongs to the technical field of solid waste recycling, and in particular relates to a process for recovering molybdenum silicon heteropolyacid from waste molybdenum disilicide.

Background technique

Molybdenum is a rare and precious metal. The reserves of molybdenum on the earth are small, and its content only accounts for 0.001% of the weight of the earth's crust. The molybdenum mines in the world are mainly distributed in the United States, China, Chile, Russia, Canada and other countries. my country's proven reserves of molybdenum metal are 8.4 million tons, ranking second in the world, and the output of molybdenum products ranks third in the world, accounting for 24% to 25% of the world's total molybdenum output.

Molybdenum has a small expansion coefficient, high electrical conductivity, and good thermal conductivity. It is not eroded by air at room temperature, does not react with hydrochloric acid, hydrofluoric acid, and alkaline solutions, and is only soluble in nitric acid, aqua regia, or concentrated sulfuric acid. It is also quite stable to most liquid metals, non-metallic slags and molten glasses. Therefore, molybdenum and its alloys have a wide range of applications and good prospects in steel, electronics, aerospace, nuclear energy technology, metal pressure processing, chemistry and other industrial fields, and have become an important raw material and an irreplaceable strategic substance in the national economy.

With the continuous expansion of molybdenum resources in the national defense industry and national economy, the demand for molybdenum and its compounds continues to increase. Only relying on the extraction of molybdenum and its compounds from molybdenum-containing metal ores can no longer meet the needs of production development, and as a limited resource, unlimited development and utilization is also impossible. Therefore, from a strategic point of view, it is necessary to realize the recycling of molybdenum resources Utilize, establish a recovery and recycling system for molybdenum-containing secondary resources, develop advanced technology for recovering molybdenum from various molybdenum-containing secondary resources and producing molybdenum products, increase the recycling rate of molybdenum, and promote the sustainable development of the molybdenum industry.

Molybdenum disilicide (MoSi ₂ ) has been highly valued by the aerospace and military sectors for its high melting point, low density, good high temperature oxidation resistance and a series of mechanical, electrical and other excellent properties, as a potential high temperature Structural materials are expected to be used in the field of high-temperature oxidation at 1200-1600 °C.

At present, the most widely used application of MoSi ₂ is as heating element of electric furnace. The MoSi ₂ heating element was invented by the Swedish Kanthal Company. In 1956, Kanthal obtained the first commercial patent for the MoSi ₂ heating element. Its representative products are Kanthal and Kanthal-Super produced by Kanthal Company. In the early 1990s, Kanthal introduced The temperature of the heating element is increased to 1900°C. China started the research on _MoSi2 heating elements in the early 1960s, and realized the industrial production of molybdenum disilicide heating elements in the 1980s. MoSi ₂ heating elements have been used in large industrial electric furnaces and small laboratory electric furnaces, and are one of the main equipment in industries such as metallurgy, electronics, glass, ceramics and magnetic materials.

At present, the global output of MoSi ₂ heating elements has exceeded 600 tons/year, and the output in China has also exceeded 300 tons/year, but the waste of molybdenum disilicide heating elements has not attracted enough attention. Therefore, more than 300 tons of molybdenum disilicide waste are abandoned or idle in my country every year. There are more than 190 tons of molybdenum (worth nearly 100 million yuan) in more than 300 tons of molybdenum disilicide heating elements in my country every year. If these wastes are recycled, the recycling rate of molybdenum will be greatly enhanced, and the sustainable development of the molybdenum industry will be greatly enhanced. Development and environmental protection have great significance, and can also bring good economic benefits.

Contents of the invention

The object of the present invention is to provide a process for recovering molybdenum silicon heteropolyacid from waste molybdenum disilicide, which solves the recycling problem of molybdenum disilicide, and has simple method, good effect and resource saving.

Processing step of the present invention is as follows:

(1) Pulverizing waste molybdenum disilicide into powders with a size of 2 to 15 microns;

(2) transfer the pulverized material into a porcelain boat, place it in a box-type resistance furnace for roasting, the roasting temperature is 400-600° C., and the roasting time is 4-10 hours to obtain a mixture of molybdenum and silicon oxide;

(3) The powder obtained after oxidation and deionized water are configured into a mixture slurry according to a weight ratio of 1:10 to 1:5;

(4) Add solid NaOH to the mixture slurry of oxidized powder and deionized water, the mass ratio of NaOH to powder is 0.5-1.2; magnetically stir at 60-90°C for 1-2h, filter after cooling, and take the filtered solution ;

(5) Adding concentrated hydrochloric acid with a mass fraction of 37.5% in the beaker in advance, the ratio of concentrated hydrochloric acid to the volume of the solution is 1: 8 to 1: 15, slowly pour the solution into the concentrated hydrochloric acid, and stir;

(6) Put the solution of step (5) into a water bath and heat at 40-80°C, and keep stirring until silica gel is precipitated, and take the solution after filtering;

(7) Add an equal volume of n-butanol to the solution of step (6) for extraction. After three extractions, the first two stand still for 10-30 minutes, and the last stand for 20-40 minutes to separate the liquid. After the liquid separation, take the above Butanol solution;

(8) The n-butanol solution obtained after three extractions is mixed, then washed three times with a saturated aqueous solution of n-butanol, and the washed n-butanol solution is subjected to vacuum distillation to obtain a molybdenum-silicone heteropoly acid product;

(9) Dissolve the molybdenum-silica heteropolyacid product in deionized water again, add a small amount of nitric acid, filter and wash off the residual n-butanol organic matter, and dry to obtain the molybdenum-silica heteropolyacid product.

Compared with the prior art, the present invention can realize the reuse of rare precious metal molybdenum and semiconductor metal silicon in waste molybdenum disilicide, and realize the strategy of resource recycling. Through the present invention, a new material - molybdenum silicon heteropoly acid. The process has strong pertinence and good effect, and has wide practicability in the recycling of waste silicon-molybdenum rods and molybdenum-silicon products.

Description of drawings

Fig. 1 is the X-ray diffraction spectrum of the product obtained in the present invention, as can be seen, according to the present invention can obtain molybdenum silicon heteropolyacid.

Fig. 2 is the macroscopic appearance of the molybdenum silicon heteropolyacid prepared in the present invention.

Detailed ways

Example 1: Pulverize waste molybdenum disilicide into 2-micron powder, then place it in an electric furnace and roast it at 600°C for 10 hours, and configure the powder and deionized water obtained after roasting into a mixture slurry according to the weight ratio of 1:10, Then add solid NaOH, the mass ratio of NaOH to powder is 0.5, stir magnetically at 60°C for 2h, filter after cooling, pour the filtrate into concentrated hydrochloric acid, the ratio of concentrated hydrochloric acid to solution volume is 1:8, stir evenly; Put it into a water bath, heat at 40°C, and keep stirring until silica gel is precipitated, then take the solution after filtration; add an equal volume of n-butanol to the solution for extraction, and perform three-stage extraction, and stand for 10 minutes for the first two times. After standing still for 20 minutes for the last time, separate the liquid, wash with a saturated aqueous solution of n-butanol, and then conduct vacuum distillation to obtain a heteropolyacid product; dissolve it in deionized water, add a small amount of nitric acid, filter and wash off the residual n-butanol organic matter, and dry Obtain molybdenum silicon heteropolyacid.

Example 2: Pulverize waste molybdenum disilicide into 15-micron powder, then place it in an electric furnace and roast it at 400°C for 8 hours, and configure the powder and deionized water obtained after roasting into a mixture slurry according to the weight ratio of 1:8. Then add solid NaOH, the mass ratio of NaOH to powder is 0.7, stir magnetically at 70°C for 1.7h, filter after cooling, pour the filtrate into concentrated hydrochloric acid, the ratio of concentrated hydrochloric acid to solution volume is 1:10, stir well; Put the solution into a water bath, heat at 60°C, and keep stirring until silica gel is precipitated, then take the solution after filtration; add an equal volume of n-butanol to the solution for extraction, and perform three-stage extraction, and stand for 15 minutes for the first two times , after standing still for 25min for the last time, separate the liquid, wash with a saturated aqueous solution of n-butanol, and then carry out vacuum distillation to obtain a heteropolyacid product; add a small amount of nitric acid after dissolving with deionized water, filter and wash away the residual n-butanol organic matter, Dry to obtain molybdosilicone heteropolyacid.

Embodiment 3. The waste molybdenum disilicide is pulverized into a powder of 12 microns, then placed in an electric furnace and roasted at 500° C. for 4 h, and the powder obtained after roasting and deionized water are configured into a mixture slurry according to a weight ratio of 1:7. Then add solid NaOH, the mass ratio of NaOH to powder is 0.8, stir magnetically at 80°C for 1.5h, filter after cooling, pour the filtrate into concentrated hydrochloric acid, the ratio of concentrated hydrochloric acid to solution volume is 1:12, stir well; Put the solution in a water bath, heat at 70°C, and keep stirring until silica gel is precipitated, then take the solution after filtration; add an equal volume of n-butanol to the solution for extraction, and perform three-stage extraction, and stand for 20 minutes for the first two times , after standing still for 30min for the last time, separate the liquid, wash with a saturated aqueous solution of n-butanol, and then carry out vacuum distillation to obtain a heteropolyacid product; add a small amount of nitric acid after dissolving with deionized water, filter and wash away the residual n-butanol organic matter, Dry to obtain molybdosilicone heteropolyacid.

Embodiment 4. Pulverize waste molybdenum disilicide into 9-micron powder, then place it in an electric furnace and roast at 450° C. for 6 hours, and configure the powder and deionized water obtained after roasting into a mixture slurry according to a weight ratio of 1:6. Then add solid NaOH, the ratio of NaOH to powder mass is 1.0, stir magnetically at 85°C for 1.2h, filter after cooling, pour the filtrate into concentrated hydrochloric acid, the ratio of concentrated hydrochloric acid to solution volume is 1:13, stir well; Put the solution in a water bath, heat at 50°C, and keep stirring until silica gel is precipitated, then take the solution after filtration; add an equal volume of n-butanol to the solution for extraction, and perform three-stage extraction, and stand for 25 minutes for the first two times , after standing still for 35min for the last time, separate the liquid, wash with a saturated aqueous solution of n-butanol, and then carry out vacuum distillation to obtain a heteropolyacid product; add a small amount of nitric acid after dissolving with deionized water, filter and wash away the residual n-butanol organic matter, Dry to obtain molybdosilicone heteropolyacid.

Embodiment 5. Pulverize waste molybdenum disilicide into a powder of 6 microns, then place it in an electric furnace and roast it at 550° C. for 7 hours, and configure the powder and deionized water obtained after roasting into a mixture slurry according to a weight ratio of 1:5. Then add solid NaOH, the mass ratio of NaOH to powder is 1.2, magnetically stir at 90°C for 1 h, filter after cooling, pour the filtrate into concentrated hydrochloric acid, the ratio of concentrated hydrochloric acid to solution volume is 1:15, stir well; Put it into a water bath, heat at 80°C, and keep stirring until silica gel is precipitated, then take the solution after filtration; add an equal volume of n-butanol to the solution for extraction, and perform three-stage extraction, and stand for 30 minutes for the first two times. After standing still for 40 minutes for the last time, separate the liquids, wash with a saturated aqueous solution of n-butanol, and then conduct vacuum distillation to obtain a heteropolyacid product; dissolve it in deionized water, add a small amount of nitric acid, filter and wash away the residual n-butanol organic matter, and dry Obtain molybdenum silicon heteropolyacid.

Claims (1)

1. a technique that reclaims molybdenum sila polyacid from waste and old molybdenum disilicide, is characterized in that; Processing step is as follows:

(1) waste and old molybdenum disilicide is ground into is of a size of the powder of 2～15 microns;

(2) material that obtains after pulverizing changes porcelain boat over to, is placed in the chamber type electric resistance furnace roasting, and maturing temperature is 400～600 ℃, and roasting time is 4～10h, obtains the mixture of molybdenum and Si oxide;

(3) powder and the deionized water that obtains after oxidation is configured to the mixture slurry according to weight ratio 1:10～1:5;

(4) add solid NaOH in the mixture slurry of the powder after the oxidation and deionized water, the mass ratio of NaOH and powder is 0.5 ~ 1.2,60～90 ℃ of magnetic agitation 1～2h, and cooled and filtered is got filtering solution;

(5) adding in advance massfraction in beaker is 37.5% concentrated hydrochloric acid, and concentrated hydrochloric acid is 1:8 ~ 1:15 with the ratio of liquor capacity, solution is slowly poured in concentrated hydrochloric acid, and stirred;

(6) solution of step (5) is put into 40～80 ℃ of heating of water-bath, and constantly stirred until there is silica gel to separate out, get its solution after filtration;

(7) add isopyknic propyl carbinol to extract in the solution of step (6), through three extractions, front twice standing 10～30min, separatory after last standing 20～40min is got top butanol solution after separatory;

(8) butanol solution that obtains after three extractions is mixed, then the saturated aqueous solution with propyl carbinol washs three times, and the butanol solution after washing is carried out underpressure distillation, obtains molybdenum sila polyacid crude product;

(9) with molybdenum sila polyacid crude product again with adding a small amount of nitric acid after deionized water dissolving, filter and wash away remaining propyl carbinol organism, drying obtains molybdenum sila polyacid product.

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