CN103361499A - Method for recovering rare earth elements from spent automobile catalyst - Google Patents

Abstract

The invention relates to a method for recovering rare earths from spent automobile catalysts. The method comprises the following steps: aging the exhausted automobile catalyst by mixing it with concentrated acid; leaching rare earth elements therein with water or dilute acid; The solution; the solution is added with alkali to adjust the pH of the solution, and a precipitant is added to precipitate the rare earth, so that the rare earth is precipitated in the form of a double salt, and the recovery of the rare earth is realized. The technical feature of the invention is that the solution after rare earth recovery is purified and returned to rare earth leaching, and the process design does not produce waste liquid. The recovery rate of rare earth is more than 90%.

Description

Method for Recovering Rare Earth from Spent Auto Catalyst

technical field

The invention relates to a method for extracting rare earths from spent automobile catalysts, and belongs to the field of secondary resource recycling of rare and precious metals.

Background technique

Rare earths have excellent optical, electrical, magnetic, superconducting, catalytic and other physical properties, and can be combined with other materials to form a variety of new materials with different properties, including rare earth permanent magnets, hydrogen storage alloy materials, luminescent fluorescent materials, and purification catalysts. New materials, including rare earths, are the largest and fastest growing consumption area of rare earths.

At present, automobile exhaust purification catalysts are the most effective means to control automobile exhaust emissions and reduce pollution. Automobile exhaust purification catalysts containing rare earths have low price, good thermal stability, high activity, good anti-poisoning ability, and long service life. At present, has been widely used. With the growing calls for environmental protection and the depletion of mineral resources, it is imperative to recycle valuable metal resources. The spent auto catalyst contains 1000~2000g/t of platinum group metals and 2~5% of rare earth elements, so it is of great research and development value for the recovery and treatment of spent auto catalysts.

The method of recovering rare earths from the catalyst is as follows:

CN102453805A discloses a method for recovering rare earth elements from spent catalytic cracking catalysts containing rare earth elements. The method uses 1-10% (wt.) hydrochloric acid solution to impregnate spent catalytic cracking catalysts at 25-80°C. Aqueous solutions of alkali metal hydroxides are contacted to obtain liquid phase products containing rare earths. The recovery rate of rare earth elements in the leaching solution is greater than 60% (wt.).

CN102453800A discloses a method for reclaiming rare earth elements from spent catalytic cracking catalysts containing rare earth elements. The method uses 1-10% (wt.) solution of hydrochloric acid and/or nitric acid to impregnate spent catalytic cracking catalysts, and the pH value of the leaching solution is adjusted to 0.5-4, extract with an organic extractant, and back-extract with a solution of hydrochloric acid and/or nitric acid to obtain a solution rich in rare earth chloride and/or nitric acid whose rare earth content and non-rare earth ion content reach GB/T4148-2003.

CN102586606A discloses a method for recovering rare earths, vanadium and nickel from spent FCC/ROC catalysts containing vanadium and nickel. The method uses 1-5mol of sulfuric acid to impregnate rare earth elements in spent catalysts at 90-95°C, and then The rare earth in the leaching solution is precipitated by salt precipitation, and after alkali conversion, it is acid-dissolved with hydrochloric acid, and then precipitated with oxalic acid and ammonium bicarbonate to obtain rare earth products.

CN102242270A discloses a method for recovering rare earth from catalyst waste residue, said catalyst waste residue is the solid waste produced in the FCC catalyst production process or the spent catalyst after FCC catalyst is used, and the catalyst waste residue is reacted with acid with a concentration greater than 0.5mol/l, Rare earths were separated by solvent extraction or oxalic acid precipitation.

CN103031438A discloses a recovery process of rare earths and precious metals in automobile exhaust gas purification catalysts. The method adopts grinding the exhausted automobile catalyst and mixing it with sodium hydroxide, roasting it between 300°C and 500°C, washing aluminum, molybdenum, vanadium, zirconium and other elements with hot water, filtering the acid-soluble rare earth elements and metal elements such as cobalt nickel iron, etc. After filtering the solution containing rare earth and iron, cobalt and nickel ions, first adjust the pH value of the solution to 3.5-4.5, then add sulfide or hydrogen sulfide to precipitate cobalt-nickel-iron at 20-40°C, and filter out cobalt The filtrate of the nickel precipitate is a solution containing rare earths, and P507 is used to extract and separate rare earths such as cerium, praseodymium, lanthanum, and yttrium, and then prepare rare earth oxides.

Judging from the disclosed methods for recovering rare earths from catalysts, they mainly focus on petrochemical catalysts. The extraction of rare earths mainly uses dilute acid to impregnate the rare earth elements in the spent catalyst, and then recovers the rare earth elements from the leachate. Sodium hydroxide roasting is used to recover rare earth elements from exhausted automobile catalysts, zirconium and other elements are leached with water, rare earths are leached with dilute acid, and rare earths are separated and recovered by solvent extraction.

Contents of the invention

The inventors of the present invention have found in research that the effect of directly impregnating the rare earth elements in the exhausted automobile catalyst with dilute acid (hydrochloric acid solution or sulfuric acid solution) is not ideal, and the concentration of hydrochloric acid is increased to 3mol/L or the concentration of sulfuric acid is increased to 4mol/L. Stirring and leaching at 85°C for 6 hours, the leaching rate of rare earth is about 50%. The reason is that the expired auto catalyst contains zirconia, and zirconia is insoluble in dilute acid, and zirconia wraps rare earth elements, hindering the dissolution of rare earth elements. In order to eliminate the above-mentioned adverse effects, the inventor of _the present invention proposes to use concentrated sulfuric acid to mix evenly with the crushed powder of the exhausted automobile catalyst, and to leach rare earth elements after aging. Soluble in concentrated sulfuric acid. Using this technical solution, the leaching rate of rare earth elements is greater than 90%, and satisfactory results have been achieved.

In order to achieve the above object, the method for reclaiming rare earths from spent auto catalysts, the technical scheme of the present invention is as follows:

Include the following steps:

Step 1: The spent auto catalyst is mixed with concentrated acid for aging;

Step 2: leaching rare earth elements with water or dilute acid;

Step 3: add a precipitating agent to precipitate and disperse the platinum group metals in the solution, and separate the solid and liquid to obtain the filtrate containing platinum group metals and rare earths;

Step 4: adding alkali to the solution to adjust the pH of the solution, adding a precipitating agent to precipitate the rare earth, and filtering to obtain the rare earth double salt.

On the basis of above-mentioned scheme, the present invention can also be improved as follows:

Further, the acid in step 1 is concentrated sulfuric acid, and the dosage is 20-200% (wt. weight) of the spent auto catalyst; the spent auto catalyst is crushed and powdered, and the particle size of the powder is greater than 200 mesh. The technical conditions of curing are: temperature from room temperature to 300° C., and time from 1 to 24 hours.

Further, the dilute acid in the step 2 is sulfuric acid, the acidity is 0-1mol/L, the reaction temperature is room temperature-90°C, the reaction time is 20-360 minutes, S:L=1:4-12.

Further, the precipitating agent in step 3 is T, the dosage is 1-5% (wt. weight) of the exhausted automobile catalyst, the precipitation temperature is room temperature-90°C, and the precipitation time is 20-240 minutes.

Further, the filtrate in step 4 is added with alkali to adjust the pH of the solution, the pH is 1-5.5, the alkali is one of magnesia and sodium hydroxide, the added precipitant is sodium sulfate, and the dosage is 1-5.5 of the rare earth in the solution. 10 times (weight wt.), precipitation temperature ranges from room temperature to 100°C, and precipitation time ranges from 20 to 240 minutes.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

1. Utilizing the mechanism that zirconia and cerium oxide are easily soluble in concentrated sulfuric acid, the concentrated sulfuric acid is used to react with the rare earth elements in the exhausted automobile catalyst, and the rare earth elements in the exhausted automobile catalyst are efficiently leached, and the recovery rate of rare earths is improved.

2. After the rare earth is extracted, the solution is purified and returned to leach the rare earth. The design of the scheme does not produce waste liquid, and the process is green and environmentally friendly.

3. Combining the present invention with the inventor's other two authorized patents (ZL200910094317.5; ZL200910094112.7), it is possible to simultaneously recover rare earths and platinum group metals from spent auto catalysts.

Description of drawings

Fig. 1 is the process flow diagram of the embodiment of the present invention.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing and specific embodiment

Example 1 See attached drawing 1, weigh 50 grams of spent automobile catalyst (containing Ce2.451%, La0.3945%) of ≥200 mesh, put it into a porcelain evaporating dish, add 16ml of concentrated sulfuric acid, mix well, and heat up to 300°C , constant temperature for 5 hours. Take it out and put it into a 500ml beaker, add 200ml of 1mol/L sulfuric acid solution, solid-to-liquid ratio S:L=1:4, put it in a water bath, add 400ml of sulfuric acid solution with pH 1, heat up to 85°C, stir at constant temperature for 6 hours, add Precipitant T (T is solid Zn), react for 2 hours, filter, the content of precious metals in the filtrate is <0.0005 g/L, put 34.88 grams of filter residue into a porcelain evaporating dish, add 12.6ml of concentrated sulfuric acid, repeat roasting and leaching once, rare earth leaching Rate Ce93.78%, La94.05%. Add sodium sulfate to the rare earth leaching solution until the concentration reaches 5% (wt), heat to 90°C for 2 hours, place for 1 hour, and filter to obtain rare earth double salts. The rare earth precipitation rates are Ce96.66% and La97.71%, respectively. The rare earth recoveries from spent auto catalysts to rare earth double salts are Ce90.65% and La91.90%, respectively.

Example 2 See attached drawing 1, weigh 50 grams of exhausted automobile catalyst (containing Ce2.451% and La0.3945%) of ≥200 mesh, put it into a porcelain evaporating dish, add 16ml of concentrated sulfuric acid, mix well, and heat up to 150°C , constant temperature for 5 hours. Take it out and put it into a 500ml beaker, add 200ml of 1mol/L sulfuric acid solution, S:L=1:4, put it in a water bath, add 400ml of sulfuric acid solution with a pH of 1, raise the temperature to 85°C, stir at constant temperature for 6 hours, add the precipitant T (T is solid Zn), react for 2 hours, filter, the precious metal content in the filtrate is <0.0005 g/L, put 37.54 grams of filter residue into a porcelain evaporating dish, add 13.5ml concentrated sulfuric acid, repeat roasting and leaching once, the rare earth leaching rate is Ce92. 17%, La 92.48%. Add sodium sulfate to the rare earth leaching solution until the concentration reaches 5% (wt), heat to 88°C for 2 hours, stand for 1 hour, and filter to obtain rare earth double salts. The rare earth precipitation rates are Ce98.75% and La98.54%, respectively. The rare earth recovery rates from spent auto catalysts to rare earth double salts are Ce91.02% and La91.13%, respectively.

Example 3 See attached drawing 1, weigh 50 grams of spent automobile catalyst (containing Ce2.451%, La0.3945%) of ≥200 mesh, put it into a porcelain evaporating dish, add 16ml of concentrated sulfuric acid, mix well, and heat up to 225°C , constant temperature for 5 hours. Take it out and put it into a 500ml beaker, add 200ml of 2 N sulfuric acid solution, S:L=1:4, put it in a water bath, add 400ml of sulfuric acid solution with pH 1, heat up to 85°C, stir at constant temperature for 6 hours, add precipitant T, React for 2 hours, filter, the precious metal content in the filtrate is <0.0005 g/L, put 36.91 g of filter residue into a porcelain evaporating dish, add 13.29 ml of concentrated sulfuric acid, repeat roasting and leaching once, the rare earth leaching rate is Ce92.57%, La 93.38%. Add sodium sulfate to the rare earth leaching solution until the concentration reaches 5% (wt), heat to 93°C for 2 hours, stand for 1 hour, and filter to obtain rare earth double salts. The rare earth precipitation rates are Ce97.45% and La97.06%, respectively. The rare earth recoveries from spent auto catalysts to rare earth double salts are Ce90.21% and La90.63%, respectively.

Claims (5)

1. the method for recovering rare earth from spent auto-catalysts is characterized in that: comprise following processing step:

1.. spent auto-catalysts mixes with concentrated acid and carries out slaking;

2.. water or diluted acid leaching rare earth element;

3.. add the platinum metals that the precipitation agent precipitation disperses to enter solution, solid-liquid separation obtains platinum group metal filter residue and contains the solution of rare earth;

4.. earth solution adds the potential of hydrogen that alkali is adjusted solution, adds the precipitation agent precipitating rare earth, filters and obtains double salt of rare earth.

According to claim 1 from spent auto-catalysts the method for recovering rare earth, it is characterized in that step 1. described concentrated acid be the vitriol oil, consumption is 20～200% of spent auto-catalysts weight; Described spent auto-catalysts is for process is broken, powder process, and powder size is greater than 200 orders; The processing condition of slaking are: temperature is room temperature～300 ℃, 1～24 hour time.

According to claim 1 from spent auto-catalysts the method for recovering rare earth, it is characterized in that step 2. described diluted acid be sulfuric acid, acidity is 0-1mol/L, temperature of reaction is room temperature～90 ℃, 20～360 minutes reaction times, solid-to-liquid ratio S:L=1:4～12.

According to claim 1 from spent auto-catalysts the method for recovering rare earth, it is characterized in that step 3. described precipitation agent be T, consumption is 1～5% of spent auto-catalysts weight, and precipitation temperature is room temperature～90 ℃, sedimentation time 20～240 minutes.

5. the method for recovering rare earth from spent auto-catalysts according to claim 1, it is characterized in that the 4. potential of hydrogen of described earth solution adding alkali adjustment solution of step, pH is 1-5.5, alkali is a kind of in magnesia, the sodium hydroxide, the precipitation agent that adds is sodium sulfate, consumption is 1～10 times of solution middle-weight rare earths weight, and precipitation temperature is room temperature～100 ℃, sedimentation time 20～240 minutes.

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