JPS6283433A - Method for separating rare earth element from alloy containing rare earth element - Google Patents

Abstract

PURPOSE:To separate rare earth element with a good recovering ratio and a low cost, by heating alloy contg. rare earth element and iron to oxidize it with air, then forming rare earth element salt by strong acid leaching and dissolving it. CONSTITUTION:Alloy contg. rare earth element and iron is heated at about 200-700 deg.C for about 0.5-2.0hr to convert iron in alloy to iron oxide resistant to dissolution in acid. The alloy is milled to about 50-200 mesh after cooling, dipped in strong acid 9about 2-5 N concon.) such as hydrochloric acid, laid as it is at room temp. for about 1hr to leach out rare earth element. Next, insoluble iron oxide is filtered, oxalic acid, sodium carbonate, etc., are added to residual filtrate to precipitate rare element. The ppt. is filtered and separated, then dried and calcined at almost 800-1,000 deg.C to obtain rare earth element oxide. In this way, quantities of acid and alkali required to extraction can markedly by decreased and rare earth element is separated with a high yield ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for separating rare earth elements from alloys containing rare earth elements and iron.

<Prior Art> In recent years, rare earth element-iron alloys have been developed as high-performance permanent magnets and have come into practical use. Examples of the components of such a rare earth element-iron alloy include about 30% by weight of rare earth elements, about 65% by weight of iron, about 2% by weight of boron, and other components. In the production of magnets, alloy waste is generated which is about 20% to 40% by weight of the product, and alloy H
Approximately 30% by weight of is a rare and expensive resource,
It is also a valuable rare earth element. Therefore, recovery of rare earth elements in alloy scrap is essential from the viewpoint of effective utilization of resources as well as from the viewpoint of economic efficiency.

According to the conventionally known rare earth element separation method, a rare earth element-iron containing alloy is first completely dissolved with a strong acid such as hydrochloric acid, nitric acid, or sulfuric acid, and then the pH is adjusted with an alkali such as sodium hydroxide, potassium hydroxide, or ammonium hydroxide. The iron in the alloy is precipitated in the form of iron hydroxide, which is then separated into individual units. Add oxalic acid to the remaining P solution.

Ammonium bicarbonate, soda carbonate, etc. are added to precipitate rare earth elements, and the precipitates are separated, dried, and fired to obtain rare earth element oxides.

<Problems to be Solved by the Invention> However, in the above-mentioned known method, an extremely large amount of acid is required because the entire amount of the rare earth element-iron-containing alloy is completely dissolved with strong acid. Furthermore, in order to precipitate a large amount of iron hydroxide, a large amount of alkali is also required, and it is difficult to separate the produced polyacid iron hydroxide from house to house. Therefore, the known methods cannot be implemented on an industrial scale.

<Object of the Invention> Therefore, the present invention [1] is an economical method that does not require the use of polyelectrolytic acids and alkalis and the treatment of iron hydroxide.
It is an object of the present invention to provide a method for separating rare earth elements from rare earth element-iron containing alloys.

Another object of the invention is to provide a method for separating rare earth elements from rare earth element-iron containing alloys which is very easy to implement on an industrial scale.

Other eleven aspects of the present invention will become apparent from the following description.

<Means for Solving the Problems> According to the present invention, after a rare element-iron containing alloy is heated and oxidized in air, a rare earth element salt is generated by an acid leaching method using a strong acid and is added to the filtrate. Dissolved in.

A method for separating rare earths from rare earth element-containing alloys is provided.

<Description of the Invention> 31 In the present invention, rare earth elements in the rare earth element-iron containing alloy from which rare earth elements are to be separated and recovered include, for example, neodymium (Nd), praseodymium (Pr), cerium (Ce), and dysporosium. (1')y), gadolinium (Gd), yttrium (Y), and other rare earth elements, and iron is contained as another component. Furthermore, it may contain cobalt (Co), boron (B), aluminum (AQ), etc.

In the present invention, a rare earth element-iron-containing alloy is first heated in an electric furnace or the like at a temperature of 200°C to 700°C, preferably 330°C.
It is desirable to heat to 0°C to 600°C for 0.5 to 2.0 hours, preferably about 1 hour.

By heating and oxidizing in air, the iron in the alloy is changed to iron oxide, which is poorly soluble in acids, and only the rare earth elements are extracted. If the temperature is lower than 200° C., oxidation of iron is insufficient and the soluble content increases. If the temperature is higher than 700°C, energy consumption will increase more than necessary, which is not preferable. The air-oxidized alloy is then cooled and then ground into 50 to 200 meshes, preferably 80 to 120 meshes. After grinding, add a strong acid such as hydrochloric acid, nitric acid, sulfuric acid, etc. to a 2-5N (normal) aqueous solution, preferably 3N.
The crushed alloy was immersed in a N to 4N aqueous solution, and the temperature was about 1 at room temperature.
Leave it for a while to leach out the rare elements. acid concentration is 2
If it is lower than 5N, the dissolution will be insufficient, and if it is higher than 5N, it will be excessive and uneconomical.

After leaching, the insoluble iron oxide is separated and oxalic acid, ammonium bicarbonate, soda carbonate, etc. are added to the remaining furnace liquid to precipitate the rare earth element salt. Since a large proportion (for example, about 65% by weight) of iron is in the form of an oxide that is soluble in acid, the amount of acid used is reduced to about 174 to 1/3 compared to conventional methods. I
- The precipitate of the rare earth element salt is filtered and separated, dried, and then calcined in an electric furnace or the like at a temperature of 800°C to 1000°C to obtain a rare earth element oxide.

If alloy scrap contains cobalt, boron, aluminium, etc., these components will be contained in the furnace solution when rare earth element salts are precipitated with oxalic acid, ammonium bicarbonate, soda carbonate, etc. Therefore, it can be separated from the sedimentary elements.

<Example> Example” - N d -F e - containing about 30% by weight of rare earth elements
Prepare four 30g B-based magnet layers for each firing temperature, place them in a porcelain boat, and heat them in an open nichrome heated electric furnace.
50℃, 200℃, 300℃, 400℃, 500℃, 6
Approximately one
After heating for an hour and cooling, pulverize into 100 meshes and apply each sample to 5N (normal)-220mQ1.41'l-1
-27O, 3N-360mQ and 2N-540mQ were added and left to stand for about 1 hour to leaching the rare earth elements with acid. Next, the insolubilized iron oxide in each sample was separated in a furnace using filter paper, and oxalic acid was added to the remaining furnace solution to precipitate the oxalates of rare earth elements. After separation by filtration, it was dried and heated in an electric furnace at 900°C. A rare earth oxide was obtained. After measuring the weight, the extraction rate of rare earth elements and iron was calculated from the values analyzed according to the JIS chemical analysis method and the amount of rare earth element salts and iron in the original magnet layer. = Calculated. The results are shown in Tables 1 to 4 below.

From the results of -1- below, the heating temperature is 300°C to 600°C,
It is clear that when the acid concentration is 2N to 5N, particularly when the acid concentration is 3N to 4N, good results are obtained in that the rare earth element extraction rate is high and the iron extraction rate is low.

Example 11 30 g of a N d -F e -r3-based magnet layer was placed in a porcelain boat and heated in an open electric furnace at 450°C for 1 hour to oxidize it. After taking it out and leaving it to cool, grind it into 100 meshes in a mortar, put it in a 500mQ beaker, and add 1.5N of hydrochloric acid. After adding OOmQ, it was left to stand for 1 hour. Thereafter, 15 g of oxalic acid was added to the solution, which was separated using filter paper, to precipitate the oxalate of the rare earth element, and the mixture was separated in a furnace, dried, and fired to obtain a rare earth oxide. The amount of the obtained oxide was 8.1 g, and the recovery rate was 90%. Also, the iron content in the oxide is 0.
．． It was 2% by weight.

Part I Communication-■ 30g of Nd-Fe-B-based spontaneous debris was placed in a 2Q beaker, and approximately 300mQ of 4N hydrochloric acid was added to completely dissolve it. Air was passed through this solution for 3 hours to oxidize the divalent iron to trivalent iron, and then about 50% of 2N ammonium hydroxide was added with stirring.
60 mQ was added and the pH was adjusted to 4. Thereafter, the iron hydroxide was filtered through a filter, and 15 g of oxalic acid was added to the filtrate to precipitate the oxalate of the rare earth element, which was then fired in a furnace to obtain a rare earth oxide.

The weight of the obtained oxide was 7.2 g, the recovery rate was 80%, and the iron content in the oxide was 0.2% by weight. <Effects of the Invention> As described above, the present invention achieved For example, when recovering rare earth elements from rare earth element-iron containing alloys, the amount of acids and alkalis required for extraction can be significantly reduced, and the amount of insoluble iron to be treated is also very small, thus making it possible to carry out on an industrial scale. is easy. Furthermore, the recovery rate of rare earth elements in the obtained rare earth element oxide is high, and the amount of iron contained is also small.

Claims (1)

[Claims] A rare earth element-containing alloy characterized in that a rare earth element-iron containing alloy is heated and air oxidized, and then a rare earth element salt is generated by an acid leaching method using a strong acid, dissolved in the filtrate, and separated by filtration. How to separate rare earths from.